UNIVERSITY OF CALIFORN 
 
 WOOD RESIDUE USES IN THE 
 CALIFORNIA PINE REGION 
 
 William A. Dost 
 
 HQVoO'QS 
 
 i i 
 
 
 
 V* 
 
 *m 
 
 CALIFORNIA AGRICULTURAL 
 EXPERIMENT STATJON 
 
 BULLETIN 817 
 
The forest products industry throughout the West, and particularly in California, 
 is undergoing rapid changes in technology, processes, and structure. One reason 
 for these changes is the increased application of technology in all industries, but 
 other reasons are undoubtedly more important — prime timber is becoming less 
 available and competition with other materials for markets is more intense. New 
 products and processes have enabled alert and aggressive firms to bargain for 
 timber supplies on an advantageous basis since they are in a position to utilize a 
 greater portion of the log brought in from the woods. As time passes, both size 
 and quality of the available timber will decrease and a greater and greater part of 
 the log will be lost to residues. Use of these residues will become increasingly 
 necessary. 
 
 This bulletin evaluates alternate uses for residues. It deals with raw material 
 requirements, capital requirements, processing and other pertinent data. It does 
 not intend to give a processor all the information he needs in order to decide on 
 a given process, but it should help him eliminate some processes as unsuited to 
 his particular operation. He can then study the more promising alternatives in more 
 detail. Unique uses for wood residues were not a goal in the study. 
 
 The available literature was reviewed to find the major uses for wood residues 
 that have been successful in the past. As a result of this review the following ap- 
 plications are evaluated in this bulletin: 
 
 Particleboard 3 
 
 Wood chips 7 
 
 Wood flour 8 
 
 Wood particle molding 11 
 
 Molding pulp products 13 
 
 Horticultural bark 15 
 
 Sawdust soil conditioners 16 
 
 Charcoal 17 
 
 Miscellaneous products 20 
 
 A method of residue determination was evaluated on residues from two sawmills 
 and one remanufacturing plant in the California Pine Region; the method and 
 results are presented in the Appendix, page 21. 
 
 THE AUTHOR: 
 
 William A. Dost is Extension Forest Products Specialist, Agricultural Extension, 
 Berkeley. 
 
 ACKNOWLEDGMENT 
 
 The author is indebted to the Cal-Ida Lumber Company for its support of this study 
 and for making available data necessary to it; and to Robert Kundrot for assistance in 
 the field study and the survey of literature. F. E. Dickinson and H. C. Sampert were 
 particularly helpful with their suggestions. 
 
 OCTOBER, 1965 
 
WOOD RESIDUE USES IN THE 
 CALIFORNIA PINE REGION 1 
 
 PARTICLEBOARD 
 
 The particleboard industry continues to grow rapidly. Yet it is plagued by excess 
 capacity and declining prices. Technology is still developing fast and the higher-quality 
 boards are accepted most readily in the market. 
 
 The minimum economical plant in the West requires 50 tons of raw material per 
 day; the optimum, 100 tons or more. However, past experience shows that any plant 
 at less than optimum at the time of construction will have difficulty remaining com- 
 petitive for an extended period. The most desirable raw material, generally speaking, 
 is green wood of lumber trim and edging size or larger. Planer shavings may also be 
 acceptable. 
 
 The manufacture of particleboard is 
 often the first possibility considered by a 
 manufacturer faced with the necessity of 
 utilizing his wood residues. The market 
 for this material has grown tremendously 
 since the first plant was installed in Ger- 
 many in 1941 and the United States in 
 1945. From this beginning, production in 
 1957 reached 183 MM sq ft on a % " basis 
 and for 1963 was 494 MM sq ft. 
 
 There are a number of specific processes 
 available. These are described in some 
 detail on pages 27-34 of Graham and 
 Parrish ( 1961 ) . a Recent installations have 
 heavily favored the production of a high- 
 quality board — a multiplaten product, 
 usually a three-layered board. Its main 
 advantages over extruded boards are its 
 better dimensional stability and the better 
 surface that can be obtained. Also, multi- 
 platen board strength is relatively uniform 
 in all directions parallel to the surface of 
 the board while extruded board shows 
 distinct differences. 
 
 The extrusion process requires a lower 
 capital investment and can operate at 
 lower production rates, but the product's 
 characteristics limit its market acceptance. 
 Consequently, most of the extrusion board 
 installations are "captive" operations in 
 which production and use conditions can 
 be well coordinated. Production of ex- 
 truded board declined by about 10 per 
 cent in the period 1957 to 1961. 
 
 Properties and uses 
 
 The uses for particleboard are expanding 
 with advancing product technology. A 
 recent study showed that 80 per cent of 
 the particleboard produced was used by 
 the furniture trade and as core material for 
 the manufacture of hardwood veneer and 
 plywood. Since that study, construction 
 uses have increased and, in 1963, more 
 than one-fourth of all U. S. production 
 was used as floor underlayment. In es- 
 sence, particleboard is used as an alternate 
 to lumber or plywood. Here, briefly, are 
 the properties required of a competitive 
 board : 
 
 • Hardness — at least equal to the ma- 
 terial it might replace. 
 
 • Density — comparable to solid wood, 
 at most no more than 25-35 per cent 
 higher. The most desired boards are 
 in the range of 40-42 lbs/cu ft. 
 
 • Stiffness — sufficient to prevent warp- 
 age of veneered panels. 
 
 • Bending strength — must be adequate 
 
 for the intended use. 
 
 • Creep resistance — equal to lumber 
 under reasonable loads. 
 
 • Tensile strength perpendicular to 
 board surface — should be adequate. 
 
 • Dimensional stability — better than 
 lumber of equal dimensions. 
 
 • Flatness — no tendencies to warpage. 
 
 • Smoothness — should not "telegraph" 
 through crossbands and veneers. 
 
 1 Submitted for publication September 4, 1964. 
 
 2 References refer to the selected bibliography at the conclusion of each section. 
 
 [3] 
 
• Gluability — bonds to veneer must be 
 strong enough so that failure occurs 
 within the particleboard. However, 
 low-strength veneers should rupture 
 internally before the particleboard or 
 the glue line. Must permit edge-glu- 
 ing, banding and veneering by the 
 same methods used with lumber and 
 plywood. 
 
 • Finishing — should accept all types of 
 paints, stains, shellacs, varnishes, and 
 waxes. 
 
 • Machining — should be easy to ma- 
 chine and permit use of carbon steel 
 tools. 
 
 • Fastening — should permit use of 
 screws in both edge and face, as well 
 as the use of nails. 
 
 Manufacture 
 
 The particleboard production process is 
 described in some detail in Graham and 
 Parrish (1961). Briefly, it includes reduc- 
 ing the wood to the desired size, drying, 
 mixing with adhesive and other additives, 
 forming into a mat, and pressing. Newer 
 plants usually incorporate a refinement 
 in the mat formation step which results 
 in a board with fine particles on the sur- 
 face. 
 
 Investment 
 
 Capital investment requirements depend 
 both on the process selected and the oper- 
 ating capacity. The extrusion process 
 should only be considered for a "captive" 
 plant. The optimum size for a multiplaten 
 process is from 20 MM to 40 MM sq ft of 
 3 A " board/year. In the West in 1962, four 
 plants operated with a capacity of less than 
 
 10 MM sq ft/year, three between 10 MM 
 and 20MM and eleven from 20 MM to 60 
 MM sq ft/year. The trend is clearly 
 toward larger operating units. 100 tons/ 
 day is equivalent to 20 MM sq ft/250-day 
 year of 40 pcf 3 A " board. 
 
 The table below presents capital costs, 
 either estimated or reported, for particle- 
 board installations of different sizes for 
 several years. A prominent particleboard 
 plant engineering and construction firm 
 indicates that, in 1963, in very general 
 terms a reasonably efficient plant did not 
 cost more than $20,000 per ton of daily 
 output. 
 
 In recent years, minimum economical 
 size has been suggested as ranging between 
 35 and 50 tons output per day or roughly 
 10 MM sq ft per year. However, western 
 plants are generally larger than this, the 
 trend appears to be to still larger plants, 
 and a high mortality rate exists in the in- 
 dustry. Consequently, a plant should be 
 planned not simply for profitability under 
 current operating conditions but also 
 should anticipate future changes. For ex- 
 ample, a recently constructed plant has a 
 60 MM sq ft capacity. 
 
 Raw Material Requirements 
 
 Minimum raw material requirements are 
 about 50 tons per day. In the West, an 
 installation of less than 100 tons output/ 
 day should be considered unusual under 
 present conditions. 
 
 Particleboards are made from a spec- 
 trum of wood residues ranging from dry 
 sawdust to green solid wood. In general, 
 dry wood residues do not make as high 
 quality a product as do green residues; 
 
 
 
 
 Estimated Capital Costs 
 
 
 
 Size 
 
 1955 
 
 1956 
 
 1959 
 
 1960 
 
 1961 
 
 1962 
 
 MM sq ft 
 
 Thousand dollars 
 
 5 
 
 7 
 
 507 
 
 705 
 
 550 
 
 650 
 800 
 900 
 
 3,000 
 
 850 
 
 1,600 
 2,000 
 
 
 8 
 
 
 10 
 
 
 12 
 
 
 15 
 
 
 20 
 
 
 25 
 
 6 000* 
 
 
 
 * Total capitalization. 
 
 [4] 
 
3 
 
 o 
 
 T 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 100- 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 — x Production 
 
 
 
 
 
 
 4 
 
 nn 
 
 
 
 _,___ Number of plants 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■1 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 / 
 
 
 
 so 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 / 
 
 / 
 
 40 - 
 
 
 
 
 
 
 
 / 
 
 » 
 
 P 
 
 / 
 
 
 — < 
 
 / 
 
 A 
 
 / 
 
 
 30 
 
 
 
 
 
 
 
 
 \ 
 
 
 1,^^ 
 
 k 
 
 / 
 
 X 
 
 
 
 
 ?0 
 
 
 
 
 
 
 
 
 
 
 J 
 
 i 
 
 10 
 
 
 
 
 t 
 
 
 1/ 
 
 > 
 
 X 
 
 \ 
 
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 a 
 c 
 a 
 
 > 
 
 
 
 l— — ' 
 
 .^.j 
 
 ^J 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 19! 
 
 <Q 
 
 .9 
 
 k 
 
 19 
 
 
 19! 
 
 >6 
 
 19! 
 
 »8 
 
 19 
 
 60 
 
 19 
 
 62 
 
 19 
 
 64 
 
 Fig. 1. United States particleboard production. 
 
 and edgings and trims or larger pieces are 
 preferred to fine pieces. 
 
 Marketing 
 
 The rate of expansion in the industry has 
 been explosive and there seems to be no 
 sign of a leveling off. But other factors, 
 too, enter the marketing picture. Figure 1 
 shows the relation between production 
 capacity and actual production. Much of 
 the unused capacity is no doubt in captive 
 plants or is obsolescent. However, its 
 existence combined with the turnover in 
 operating firms indicates that the tech- 
 nology is still developing fairly rapidly 
 and that competitive pressures are high. 
 
 Recent price trends (figure 2) show a 
 decline but a substantial portion of this 
 may be ascribed to improved manufac- 
 turing techniques resulting in lower pro- 
 duction costs. The price picture empha- 
 sizes the necessity of designing new plants 
 for adaptability while holding production 
 costs as low as possible. 
 
 Freight rates represent a substantial 
 fraction of the total price to the customer, 
 $46/M sq ft 3 A " bd delivered to the East 
 Coast. Therefore, the location of a plant 
 with respect to its competitors and its 
 markets is of utmost importance. 
 
 Each manufacturer of particleboard for 
 the competitive market seems to provide 
 
 [5] 
 

 
 
 1 1 
 
 1 
 
 _ Max 
 
 1 
 
 1 1 1 
 
 *»nd u<ier (warehoused 
 
 
 
 
 
 
 
 
 \ 
 
 
 __ — — . Delivered to industrial user or warehouse 
 
 F.O.B. mill 
 
 
 
 200 
 
 \ 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 
 
 \ 
 
 V 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 
 — %" basis 
 o 
 
 \ 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 
 \ 
 \ 
 
 \ 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 
 U. 
 CO 
 
 £ 160 
 
 \ 
 
 \ 
 \ 
 
 
 
 
 
 
 
 
 
 
 
 "o 
 Q 
 
 
 \ 
 \ 
 \ 
 
 
 
 
 
 
 
 
 
 
 
 
 140 
 
 
 
 
 *""■■»«, 
 
 ~-- 
 
 - - , 
 
 • -» _ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ""■ « 
 
 "--* 
 
 * *- 
 
 120 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1957 1958 1959 1960 1961 1962 1963 
 
 Fig. 2. Approximate price movement, medium-density particleboard. Source: Purifoy, 1963. 
 
 technical service in one form or another to ingly important and intensive. Most fre- 
 its customers. There are indications that quently, it takes the form of technical 
 this technical service is becoming increas- personnel located in the consuming areas. 
 
 References 
 
 Anonymous 
 
 1958. Wood particle board. White Plains, N.Y., Reichhold Chem. Inc., RCI Bldg. 
 
 1960. Particleboard. Vancouver, Sandwell and Company, Ltd., B.C. Development 
 Memo. 12.09-16. 
 
 1961. Current industrial reports — particleboard. Washington, D.C., U. S. Dept. of 
 Commerce. 
 
 1962. Particleboard industry — facts and references. Lafayette, Ind., Coop. Ext. Serv. 
 Purdue Univ. Mimeo. F-42. 
 
 1962. Particleboard industry outlook for 1963 and review. Washington, D.C., U. S. 
 Dept. of Commerce. 
 Chiang, T. I. 
 
 1959. Wood particle board — a manufacturing opportunity in Georgia. Atlanta, Ga., 
 Georgia Inst, of Tech. for Georgia Dept. of Commerce (March). 
 
 Graham, P. H. 
 
 1961. Particle board — its development, processes, properties, markets. Hitchcock's 
 Wood Working Digest 63(4) : 30-35. 
 Graham, P. H., and F. T. Parrish 
 
 1961. The economic possibilities of wood particleboard manufacture in Maine. 
 Augusta, Me., State of Maine Dept. of Econ. Dev. (June). 
 
 [6] 
 
Johnson, E. S., editor 
 
 1956. Wood particleboard handbook. Raleigh, N. C, North Carolina State College, 
 303 pp. 
 
 Kay, I. B. 
 
 1959. How profitable is particle board? Pulp and Paper Mag. of Canada, Tech. Sec, 
 P. T. 199 (July). 
 
 Marra, G. C. 
 
 1958. Particleboards — classification and composition. For. Prod. Jour. 8(12):11A. 
 
 Purifoy, W .R. 
 
 1963. Charting particle board's road to prosperity. Wood & Wood Prod. 68(9) : 
 41-44. 
 Schwartz, H., and F. W. King 
 
 1961. Use of wood and wood residues in production of fiberboard and particleboard. 
 Ottawa, Canada. For. Prod. Res. Branch. Tech Note 31:1-16. 
 
 Smith, C. L. 
 
 1962. The growth of the particleboard industry. Washington, D.C., U. S. Dept. of 
 Commerce, Construction Rev. 8(11): 8-10. 
 
 WOOD CHIPS 
 
 The consumption of wood chips for pulp and paper manufacture in California can be 
 expected to increase tremendously within the next few years. Mills now planned or 
 under construction within the State will approximately triple the current rate of wood 
 consumption for pulp. The industry also competes with hardboard and particleboard 
 for the same raw material. Combined with the decline in the number of operating saw- 
 mills reported by the Pacific Southwest Forest & Range Experiment Station, these pulp 
 installations portend an increasing competition for mill residues. As prices increase, 
 chip production will become feasible at smaller mills. Chip yields ranging from as low 
 as 0.25 unit/MBF of logs processed to as high as 0.75 unit/MBF have been reported. 
 
 Properties and uses Capital investment 
 
 High-quality wood chips are used for both The reported costs of one installation for 
 paper and hardboard. Also, particleboard the production of wood chips from saw- 
 plants operate on particles produced from mill residues are as follows : 
 similar residues. To be suitable for these Sawmill barking and chipping plant in- 
 uses, the chips must be of "engineered" eluding installation 
 
 dimensions. They must be screened to 
 remove fines and oversize chips, and bark 
 
 Structures $43,000 
 
 and decayed wood must be held to a mini- debarker (34" ring type) . 64,000 
 
 mum. Dirt and charred wood are not debarker transfers, 
 
 acceptable. 
 
 conveyors, etc 33,000 
 
 Chipper 19,000 
 
 Manufacture Chipper conveyors, 
 
 The manufacture of wood chips begins at screens, etc 18,000 
 
 the debarker, before the logs enter the mill. Chl P loading 
 
 If a debarker is not available, then bark- and compaction . . . 27,000 
 free pieces must be picked by hand from Total cost .... $204,000 
 the refuse conveyors and fed to the chip- 
 per. After passing through the chipper, the In addition, it would be necessary to 
 chips are screened to remove the over- either contract for or purchase the neces- 
 and undersized pieces. The fines and over- sary trucks for delivery of chips to a rail 
 sized pieces are discarded. Chips are then siding or to the purchaser if the sawmill 
 ready for shipment. was not located at a rail siding. 
 
 [7] 
 
WOOD FLOUR 
 
 The production of wood flour appears to require art as well as technology. Of primary 
 importance is a good source of raw material — sawdust and shavings of the right species 
 and moisture content. Sander dust is increasingly being recovered and used as wood 
 flour. The product may vary from manufacturer to manufacturer, even when similar 
 species and processes are used. The principal uses are as absorbents and fillers. It 
 competes with similar materials from other sources and with wood flour imports. 
 Reported prices had not changed noticeably between 1947 and 1963. 
 
 Much of the data presented in the following sections is taken from Reineke (1947). 
 
 Information on the manufacture of 
 wood flour is difficult to obtain. Relatively 
 few articles and reports on the subject 
 were written before 1945. Statistics on 
 wood flour production are limited. The 
 U. S. Census Bureau published data during 
 the 1930's but then discontinued the prac- 
 tice. Census Bureau figures show national 
 utilization of 19,000 tons in 1935, 28,000 
 tons in 1937 and 49,000 tons in 1939. 
 Imports during this period were signifi- 
 cant. The Western Pine Association stated 
 that 80,000 tons were utilized in 1947 and 
 100,000 tons in 1950. California Forest & 
 Range Experiment Station figures put 
 California utilization at 21,000 tons in 
 1952. 
 
 Producing plants contacted expressed 
 pessimism about future markets. On the 
 other hand, those articles that have ap- 
 peared recently have generally expressed 
 optimism based upon projections for the 
 consuming industries, primarily plastics 
 molding. However, an expert in the field 
 of plastic resins, when asked about the po- 
 tential of wood flour production, suggested 
 particleboard as a more promising use for 
 residues. He pointed out that the manufac- 
 turing of molded toilet seats, a major 
 market for wood flour, was so dominated 
 by a few large producers that a successful 
 entry into this market would be very 
 difficult. 
 
 Properties and uses 
 
 Three grades of wood flour are generally 
 recognized, Technical, Non-Technical, 
 and Granulated or Special Purpose. Tech- 
 nical grade normally must pass a specified 
 60-mesh or finer screen and usually must 
 be of a single species. Non-Technical 
 grade is much less restrictive, allowing 
 coarser particles, a wider range in par- 
 
 ticle size, and a mixture of species. Granu- 
 lated or Special Purpose grade specifica- 
 tions are more restrictive than Technical 
 grade. Granulated is frequently ground to 
 a finer mesh than Technical, and the parti- 
 cle shape and weight are specified. 
 
 Required properties are light color, low 
 resin content, and moisture content of 9 
 per cent or lower. The white pines (sugar, 
 western, and northern) satisfy the color 
 and resin requirements to the extent that 
 75 per cent of the flour produced domes- 
 tically comes from these species. Other 
 species used are spruce, poplar, birch, 
 maple, hemlock, Douglas-fir, and cedar. 
 While not listed as a raw material species, 
 true firs would probably yield flour similar 
 to hemlock. 
 
 Wood flour is generally used as : 
 
 Absorbents 
 
 Chemically reactive substance 
 
 Chemically inert filler 
 
 Modifier of physical properties 
 
 Mild abrasive 
 
 Decorative material 
 Of these, the principal uses are as an 
 absorbent in dynamite and as a filler in 
 linoleum and molded plastic products. 
 
 Raw material requirements 
 
 Most wood residues are unsuitable for 
 wood flour manufacture because of spe- 
 cies, contamination by bark or knots, or 
 moisture content. Ponderosa pine would 
 probably cause problems in subsequent 
 molding because of its resin content, par- 
 ticularly if flour were to be manufactured 
 from box trim ends. Sugar pine sawdust 
 and planer shavings would make an ideal 
 raw material source if the moisture con- 
 tent were sufficiently low. Douglas-fir and 
 white fir sawdust and shavings also could 
 be used for lower-quality flours. 
 
 [8] 
 
No information on minimum or opti- 
 mum size was found in the literature. A 
 capacity of 1 ton per hour was the lowest 
 production rate noted. 
 
 Manufacture 
 
 Processes — Wood flour is produced either 
 by reclamation of sander dust or the 
 screening of sawdust or, by attrition, ham- 
 mer or roller milling. An attrition mill is 
 an efficient method of producing most 
 types of wood flour. The hammer mill is 
 practically limited to flour no finer than 
 100 mesh because of the low mass of the 
 finer particles. Roller mills which crush the 
 wood are able to produce exceedingly fine 
 flours up to 350-400 mesh size. 
 
 Two methods are used in sizing of the 
 product. The original method uses oscil- 
 lating screens much as those used for the 
 sizing of pulp chips. Its main disadvantage 
 is that occasionally slivers produced in 
 hammer mills may pass through the 
 screen. These slivers are a defect in flour 
 for use in plastics molding. Air screening, 
 the other method of separation, usually 
 results in a higher percentage of fines and 
 may also contain relatively larger broomed 
 particles than mechanically screened flour. 
 It appears that either method can yield an 
 acceptable flour for most purposes. The 
 final product is bagged or baled for ship- 
 ment. More detail on wood flour produc- 
 tion is presented in Reineke (1947). 
 Power requirements — Power costs in- 
 crease with machine size. Production ca- 
 pacities of equipment vary inversely with 
 the ratio between the meshes. At the 100 
 or finer mesh sizes, power consumption 
 varies directly and output varies inversely 
 as the square of the ratio of the meshes. 
 Total power requirements are about 125 
 
 hp hours to reduce a ton of white pine 
 shavings to 40 mesh while 400 hp hours 
 are required to produce a ton of 80 mesh. 
 Special hazard — Fire hazard is great in 
 a wood flour plant because of the fine 
 particle size. Under the right conditions, 
 air-wood flour mixtures are explosive. 
 Because of this, every effort must be made 
 to eliminate sources of ignition such as 
 smoking, sparking in electrical equipment, 
 etc. Cleanliness is imperative to minimize 
 damage resulting from fires which do 
 occur. 
 
 Investment 
 
 The U. S. Forest Products Laboratory 
 report (Reineke, 1947) indicates that the 
 equipment for the production of 1 ton per 
 hour of 40-mesh flour would cost between 
 $5,000 and $8,000. Attrition and roller 
 mills are both somewhat more expensive 
 than hammer mills but attrition mills have 
 lower power and maintenance costs. Unit 
 cost of the equipment is reduced for larger 
 size machines. 
 
 Correspondence with present wood flour 
 manufacturers indicates that the minimum 
 investment for a wood flour plant might 
 be as much as $150,000. However, this 
 figure would include the buildings and 
 accessory equipment. 
 
 Marketing 
 
 Prices reported for 1947 were $20 to $25 
 per ton for 40-mesh, $35 to $40 per ton 
 for 100-mesh, and up to $85 per ton for 
 finer meshes and special grades. Current 
 prices for wood flour reported by present 
 producers and users are about in the same 
 range, $25 per ton and less for the coarser 
 mesh material. 
 
 References 
 
 Anonymous 
 
 n. d. Wood flour. Chicago, 111., Prater Pulverizer Co. 4 pp. 
 Bowen, P. P. 
 
 1957. Manufacture and use of wood flour: Wood waste. For. Prod. Res. Soc. Wood 
 Tech. Ser. 22:47-48. 
 Emmett, J. A. 
 
 1938. Wood flour production: Possibilities as a profitable means of waste utilization. 
 The Timberman 39 ( 9 ) : 9 1 . 
 Gangloff, W. C. 
 
 1963. Fillers in the plastics industry. Chem. Ind. 53(4) :512. 
 
 [9 
 
Jahn, E. C. 
 
 1939. Wood flour market expanding. West Coast Lumberman 66(7) : 40. 
 
 Reineke, L. H. 
 
 1947. Wood flour. Madison, Wise., U. S. For. Prod. Lab. FPL No. R1666-9. 
 
 Seymour, R. B. 
 
 1962. Fillers for moulding compound. Mod. Plastics, 1962 Encyclopedia Issue 39 
 (1 A): 556-60. 
 Schulman, J. and B. L. Wilner 
 
 1960. New uses for wood flour in rigid polyurethane foams. For. Prod. Jour. 10 ( 10) : 
 487-90. 
 Wilner, J. R. 
 
 1956. Wood flour: Past, present and future of utilization. For. Prod. Jour. 6(8) : 17 A. 
 
 Fig. 3. Pine log in head rig. 
 
WOOD PARTICLE MOLDING 
 
 Whereas the manufacture of wood flour for sale on the open market does not appear 
 to be particularly attractive in view of the essentially static price situation for the last 
 15 years, the limited number of available customers, and the relative remoteness of 
 most California mills as compared with those that could be located in either Los Angeles 
 or San Francisco, the combination of a wood flour plant plus a wood particle molding 
 plant might prove worthwhile. However, profitable operation depends on long produc- 
 tion runs because of the cost of molds; thus, the products to be manufactured must be 
 selected with care. If a promising product line can be selected, this approach should 
 be seriously considered. 
 
 The principal use for wood flour, as the 
 basic component in molded articles, ap- 
 pears to be expanding. In this process, the 
 wood flour is mixed with an appropriate 
 amount of thermosetting resin, introduced 
 into a heated compression mold, and 
 pressed. The wood flour can comprise as 
 much as 95 to as little as 50 per cent of 
 the resin-flour mixture. Molding pressures 
 are between 1,000 and 2,000 psi and mold- 
 ing temperatures are usually held below 
 350° F to prevent charring. The process 
 differs from particleboard production in 
 that hardened steel molds are used rather 
 than flat polished plate, and the resin con- 
 tent is higher. 
 
 At present molded wood is used mainly 
 for toilet seats. Other products are hamper 
 tops, brush backs, school furniture, appli- 
 ance bases, furniture parts, sporting goods 
 handles, etc. In general, a molded-wood 
 article might be competitive with any 
 article made from solid wood if its pro- 
 duction includes a substantial number of 
 operations or if the waste factor is high. 
 Potentially, a molded-wood article would 
 be lower in cost and could replace a 
 molded-plastic article if it could meet the 
 use requirements. 
 
 Properties and uses 
 
 The properties of molded wood articles 
 can be varied over a wide range through 
 changes in formulation and processing. 
 Important for the finished article are im- 
 pact strength, screw holding power, water 
 absorption, color, surface hardness, and 
 finishing characteristics. These properties 
 can all be manipulated by formulation. 
 Changes in formulation also result in 
 
 changes in process characteristics such as 
 cure time and press cycle. 
 
 In general, molded wood is harder, 
 heavier and more amorphous than natural 
 wood. It has no grain, which eliminates 
 weaknesses of certain types, but it also re- 
 duces the beauty of the article and the 
 strength of the material compared to na- 
 tural wood. The surface is harder and 
 more impervious to liquids but the un- 
 coated surface of the molded wood is less 
 resistant to wear. The dimensional stability 
 of molded wood under conditions of 
 changing humidity is better than tangential 
 or radial stability of natural woods but 
 most woods have better stability in the 
 direction along the grain. The molded 
 product also has a lower rate of absorption 
 in direct contact with water but, given 
 time to penetrate, the water causes greater 
 damage to the physical properties of 
 molded than natural wood. 
 
 Manufacture 
 
 The process itself is relatively straightfor- 
 ward. The wood flour is introduced into 
 the blending equipment, followed by the 
 other materials included in the formula- 
 tion. In addition to the resin, parting 
 agents, water repellents, and pigments are 
 often included. Blending requires 15-30 
 minutes when no pigment is included and 
 30 minutes to one hour when pigment is 
 added. Depending upon the particular 
 plant and equipment, the blend may then 
 be delivered directly to the mold for press- 
 ing or it may be first preheated and pre- 
 pressed. Preheating melts the resin, result- 
 ing in a better coverage of the wood 
 particles, and also advances the resin, 
 
 [ii] 
 
reducing the cure time. Prepressing con- 
 solidates the wood-resin mixture, reducing 
 the bulk and facilitating the mold-charging 
 operation. Mold temperature is usually 
 maintained between 280° and 350° F 
 depending upon the resin used. Pressures 
 of 500 to as high as 3,000 psi are common, 
 and for some special shapes 4,000 to 5,000 
 psi are used. Molds are usually manufac- 
 tured from tool steel. Specific gravity is 
 controlled by the charge into the mold 
 since the molds are closed to stops. 
 
 Resins used are melamine, phenol, and 
 urea. Urea is the lowest in cost but also 
 results in the lowest product properties, 
 particularly water resistance and perme- 
 ability. It requires a somewhat shorter 
 press cycle. Phenolic resins are more ex- 
 pensive than urea but give improved water 
 resistance and surface characteristics. 
 Phenolic resins result in a somewhat 
 darker molded article, which frequently is 
 undesirable. Melamine resins are the most 
 expensive but result in the most satisfac- 
 tory properties in the end product. 
 
 Raw material requirements 
 
 Wood flour used is generally in the range 
 of 40-100 mesh, with 80 mesh being the 
 most common size. Where surface 
 smoothness and appearance are not im- 
 portant, coarser sizes may be used with 
 excellent results. While some references 
 state that any species except oak may be 
 used as a source of wood flour, hardwoods 
 generally give somewhat different prop- 
 erties than do softwoods and each species 
 differs somewhat in the results obtained. 
 In general, hardwoods give a better 
 mold release and a faster cure because 
 they have no resin, but are more expensive 
 than softwood flour. Mechanical strength 
 usually is somewhat lower than with soft- 
 wood but water absorption and surface 
 hardness characteristics are better. Soft- 
 wood flour results in higher-strength 
 moldings but it is more bulky, requiring 
 deeper loading wells in the mold and com- 
 plicating the charging operation. The 
 resins in softwood are thermoplastic and 
 act as plasticizers for the molding resin. 
 This retards the cure rate and tends to 
 reduce the mold release. In addition, it 
 may result in a surface that is more diffi- 
 cult to finish. 
 
 Moisture content is critical. A moisture 
 content of less than 4 per cent tends to 
 restrict the flow of the molding mixture in 
 the press and also to reduce strength. 
 Moisture content higher than 8 per cent 
 will cause blisters during the molding 
 operation and prolong the cure. 
 
 The mixture of species cut in most pine 
 region mills could probably be accom- 
 modated in an associated molding opera- 
 tion but any fluctuations in species per- 
 centage throughout the year would neces- 
 sitate frequent adjustment of the molding 
 formulation. Evidence in the literature in- 
 dicates that trims from pine box manufac- 
 ture would probably contain too much 
 resin to be a satisfactory source of raw 
 material. 
 
 Investment 
 
 Only one detailed estimate for capital in- 
 vestment was obtained. This estimate was 
 for a plant processing a maximum of 40 
 tons of wood flour per eight-hour shift 
 when all of the molded articles were rec- 
 tangular shapes of optimum size. Allow- 
 ance should be made for less than opti- 
 mum shapes. This estimate follows: 
 
 EQUIPMENT 
 
 6 presses — $5,000 each 
 
 (capacity 150 pes 
 
 l"x2i/ 2 'x2i/2' 
 
 per press hour) $ 30,000 
 Press accessories (pumps, 
 
 valves, pipes, wiring, 
 
 timers, etc.) . . 2,000 
 
 6 molds .... 20,000 
 Mixing equipment 4,000 
 
 Exhaust fans and 
 
 ducts .... 2,000 
 
 $58,000 
 
 BUILDING 
 
 Press operation area 
 Raw material storage 
 Finishing .... 
 
 1,000 sq ft 
 750 sq ft 
 750 sq ft 
 
 2,500 sq ft 
 
 Cost at $8.00/sq ft $20,000 
 
 CONTINGENCIES 
 
 Contingencies $ 7,000 
 
 Grand total:. . . $ 85,000 
 
 [12] 
 
POWER 
 
 Steam— 6 boiler hp (120-150 psi) 
 Electricity — 30 hp 
 
 Marketing 
 
 Molded wood products have a definite 
 competitive area. The least expensive 
 plastic molding materials are priced about 
 $10 per cu ft, excluding cellular types. A 
 wood flour molding mixture at a specific 
 gravity of 1.0 costs approximately $3 to 
 $4 per cu ft, roughly the same price as 
 kiln-dried lumber. When a molded wood 
 article can be fabricated without too much 
 difficulty, it very likely will be competitive 
 with the corresponding article molded out 
 of solid plastic. When an article fabricated 
 from solid wood requires a number of 
 
 machining steps or the removal of a large 
 percentage of the original material, the 
 corresponding molded article also is likely 
 to be competitive. One report indicates 
 that, in general, if 25 per cent of the wood 
 or more has to be cut away in a solid wood 
 part, molding will be lower in labor cost. 
 Beyond this, there is very little similarity 
 between the marketing of molded products 
 and conventional building materials. The 
 relatively high cost of molds requires that 
 materials to be molded be scheduled for 
 long runs. To market molded wood prod- 
 ucts successfully, one must find articles 
 that can be manufactured from wood 
 flour, have advantages in properties or 
 manufacture, and that will have extended 
 production runs. 
 
 References 
 
 Anonymous 
 
 n. d. Granulated wood molding. St. Louis, Mo., Monsanto Chem. Co. Prod. Inf. 
 Bui. 1027. 
 
 1959. Wood particle binder resins: Wood flour utilization. New York, Cyanamid 
 Tech. Data Bui. II, 12 pp. 
 
 Brockschmidt, K. W. 
 
 1960. Fundamentals of molding wood particles. For. Prod. Jour. 10(4) : 179-83. 
 Donohue, F. J. 
 
 1961. Granulated wood molding. Ind. Woodworking 13(7). 
 Midyette, L. 
 
 1957. Wood particle molding. For. Prod. Jour. 7(1): 1-6. 
 Watson, D. W. 
 
 1959. Low cost wood-particle moldings. Materials in Design Eng. 49(5) : 103-05. 
 Williams, F. H., and J. Grano 
 
 1954. The manufacture of molded articles from resin bonded granulated wood. For. 
 Prod. Jour. 4(5): 227-30. 
 
 MOLDING PULP PRODUCTS 
 
 The consumption of wood pulp for plate, dish, and tray stock has increased rather 
 consistently during the past 15 years, as shown below (U. S. Census data). Indications 
 are that the market will continue to expand. 
 
 Plate, 
 
 Year 
 1946 
 1947 
 1948 
 1949 
 1950 
 1951 
 1952 
 1953 
 
 Dish, and 
 
 Short tons 
 2,696 
 18,674 
 7,977 
 21,614 
 32,380 
 27,872 
 31,367 
 62,651 
 
 Tray Stock 
 
 Year Short tons 
 1954 65,201 
 
 1955 
 1956 
 1957 
 1958 
 1959 
 1960 
 1961 
 
 83,404 
 87,747 
 94,841 
 99,126 
 99,286 
 116,996 
 119,014 
 
 The molded pulp industry is by nature 
 secretive. Few useful articles have ap- 
 peared in the literature and it is accepted 
 industry practice to close plants to visitors. 
 Consequently, the information presented 
 here represents relatively little reported 
 experience. 
 
 The minimum plant size is reported to 
 be about 50 tons of product per day. The 
 critical problems in pulp or paper produc- 
 tion are water supply and effluent disposal. 
 
 [13] 
 
Semi-chemical pulp has a process water 
 requirement of 10,000 to 30,000 gallons 
 per ton of product. The cost of a semi- 
 chemical pulp mill without liquor recovery 
 facilities was estimated at $20,000 to 
 $30,000 per ton in 1954. A California in- 
 stallation with a rated capacity of 75 tons 
 per day plus converting facilities report- 
 edly cost $25,000,000 in 1956, and a 
 
 recently installed California converting 
 plant, using waste paper as a furnish, cost 
 an estimated $10,000,000 for a 100 ton 
 per day capacity. From these rather 
 meager data, it would seem that the com- 
 bination of process water requirements, 
 effluent disposal and capital investment 
 makes this approach to residue utilization 
 relatively unattractive for most operations. 
 
 References 
 
 Anonymous 
 
 1954. Pulp manufacturing factors. Madison, Wise, U.S. For. Prod. Lab. 89 pp. 
 
 1960. Nonplastic molded pulp products. Madison Wise, U.S. For. Prod. Lab. Rept. 
 1964 (rev.). 
 
 Applefield, M. 
 
 1956. The utilization of wood residues for pulp chips. College Sta. Texas. Texas For. 
 Serv. Bui. 49. 121 pp. 
 
 Fogh, I. F. 
 
 1961. An evaluation of the economics of supplying sawmill (waste) chips to pulp 
 and paper mills. Pulp Paper Mag. of Canada 62(2) : 95-101. 
 
 Jacobson, Gus 
 
 1955. New developments in mechanical equipment for sawmill waste utilization. 
 For. Prod. Jour. 5(5) :35A-38A. 
 
 Otis, B. 
 
 1957. Diamond Match applies groundwood-from-chip pulping to softwoods. Paper 
 Trade Jour. 141(7) :36-39. 
 
 Textor, C. K. 
 
 1957. Second progress report on the Bauerite process for "Groundwood" from chips. 
 Springfield, Ohio, The Bauer Bros. 
 
 Fig. 4. By debarking logs prior to sawing, it is possible to recover both bark for horticul- 
 tural markets and wood chips for pulp production. 
 
 [14] 
 
HORTICULTURAL BARK 
 
 The use of true fir and pine bark for landscaping and horticultural purposes is increas- 
 ing and demand at times exceeds the supply. Prices are held in check by the availability 
 of other materials and by landscaping techniques. Even so, the minimum price at the 
 mill is more than twice that received for an equivalent volume of plup chips. One mill 
 reports a sales price of over $4.00 per yard, or roughly five times the price of an equiva- 
 lent volume of pulp chips. 
 
 The other benefits of sawing debarked logs — higher production of pulp chips, greater 
 recovery, reduced saw maintenance, and lower clean-up costs — have been well estab- 
 lished. The attractive market for bark as well as chips suggests that debarking should be 
 adopted if at all possible. 
 
 The field study showed that approximately 20 cu ft of fir and pine bark are generated 
 per MBM of logs cut. A net yield of 14 cu ft/MBM after processing losses has been 
 reported, equivalent to more than 650 cu yd/MMBM of production. 
 
 Actual statistics on the production or 
 sale of bark for agricultural purposes seem 
 to be nonexistent. However, an increasing 
 number of mills, some starting more than 
 ten years ago, are disposing of this part 
 of their residues to an expanding market. 
 Brokers have indicated that they could 
 move additional quantities of bark if it 
 were available. A Bay Area dealer in bulk 
 quantities indicates that the market for 
 the coarser grades is exceptionally good 
 and expanding. Packaged tree bark for 
 consumer trade was almost nonexistent a 
 few years ago, but the product is now 
 readily available at the retail level. 
 
 Properties and uses 
 
 Three generally accepted segregations of 
 bark are Va" minus, X A" to %", and 5 /s" 
 to Ws" sizes. There is some specialty 
 demand for lVs" to 3" size. Special-pur- 
 pose grades such as orchid-culture med- 
 ium also exist. The least desirable grade is 
 the fines, and the quantity produced is 
 generally held to a minimum. Bark to be 
 sold as a soil conditioner is often pulver- 
 ized and composted first. Nitrogen is 
 added to speed the process. Cutter-head 
 barkers can produce only fine material, 
 which may be composted although the 
 relatively large percentage of wood con- 
 tained makes nitrogen requirements 
 higher. 
 
 Barks of the pines and true firs are 
 generally preferred. Douglas-fir bark con- 
 tains short fibers which cause skin irrita- 
 tion, and is acceptable only in restricted 
 markets. 
 
 Manufacture 
 
 The production of horticultural bark is 
 relatively simple. The bark is first removed 
 from the log, screened to remove sawdust 
 and dirt, broken down to the desired size 
 and rescreened. Oversize particles are re- 
 cycled back through the hog and screen. 
 As previously mentioned, fines are held to 
 a minimum and freedom from wood 
 particles is important. Processing costs of 
 55 cents per yard or $4.15 per unit are 
 reported for an efficient operation. 
 
 Because of the market demand for the 
 larger sizes, a ring-type debarker is most 
 satisfactory. Screens of the oscillating 
 type similar to those used for pulp chips 
 are best but trammel screens appear to be 
 adequate and cheaper in initial cost. Fol- 
 lowing screening, the bark is delivered to 
 storage bins. 
 
 Investment 
 
 Generally, the production of bark is 
 coupled with the production of pulp chips, 
 and investment charges properly should be 
 divided between the two. Principal items 
 required for bark production, exclusive of 
 a debarker, are conveyors, hog, screens, 
 and storage. For a plant processing 75 M 
 to 150 M bf/day, this probably would cost 
 between $20,000 to $30,000 although 
 some installations at two to three times 
 this cost have been reported. In addition, 
 space for composting or bulk storage of 
 accumulated inventories is usually neces- 
 sary. 
 
 [15] 
 
Marketing keting organization, in some cases to 
 
 Market prices reported for bulk quantities brokers, and in some cases to distributors, 
 
 at the mill were a low of $.50 per cu yd for Shipments are usually made by truck, and 
 
 bark sold to processing plants to as much the major markets are in the Bay Area 
 
 as $5.50 per cu yd for fully processed and Los Angeles. Bark weighs 500-800 
 
 bark, the equivalent of $3.70 to $40.75 pounds per cu yd and transportation com- 
 
 per unit. Bark is sold in some cases to prises a substantial part of the delivered 
 
 other mills or processors that have a mar- price. 
 
 References 
 
 Baker, K. F., editor 
 
 1957. The U. C. system for producing healthy container-grown plants. Univ. of Cali- 
 fornia Manual 23. 
 
 Bollen, W. F., and D. W. Glennie 
 
 1963. Fortified bark for mulching and soil conditioning. Oregon State Univ. Agr. 
 Exp. Sta. Tech. Paper 1665. 
 Dunn, S. 
 
 1956. The influence of waste bark on plant growth. Univ. of New Hampshire 
 Agr. Exp. Sta. Bui. 435. 
 Ivory, E. P. 
 
 1958. Yields and preparation of bark from a medium sized sawmill. N. Calif. Sect., 
 For. Prod. Res. Soc. Proc. (May, mimeo.) 
 
 Kohl, H. C. 
 
 1958. Use of bark for soil improvement. N. Calif. Sect., For. Prod. Res. Soc. Proc. 
 (May, mimeo.) 
 
 Lunt, O. R., and B.Clark 
 
 1959. Horticultural applications for bark and wood fragments. For. Prod. Jour. 9 
 (4):39A-42A. 
 
 SAWDUST SOIL CONDITIONERS 
 
 Considerable volumes of redwood sawdust, and to a lesser extent Douglas-fir and other 
 species, are used as a mulch or soil conditioner in landscaping and floriculture. This 
 use is well established and acceptance is increasing. Studies seem to indicate that most 
 other species (at least most other softwoods) could be used also. 
 
 Sawdust has been used as a soil conditioner for many years and numerous publica- 
 tions have been written on the subject. Until quite recently, however, high-quality 
 sphagnum peatmoss was available at a reasonable price, and the established practice 
 of using peatmoss restricted the use of sawdust. As quality peatmoss becomes more 
 expensive and sawdust-use techniques become more widely established, acceptance is 
 increasing. 
 
 Organic material in the soil improves Manufacture 
 
 plant growth by improving water-holding Sawdust is usually screened to remove 
 
 capacity, aeration, and tilth; as it disinte- larger pieces of wood It may then ^ 
 
 grates, it adds humus to the soil but loses soM in bulk sacked as mw sawd Qr 
 
 most of its aerating and water-holding , 1 £ , „* . , 
 UJ1: . T + , i *■ -x composted before sale. Chemicals are 
 ability. In the process, it also ties up nitro- * . , , , t . 
 gen. This nitrogen drain is heaviest shortly Wintry added to counteract the mtro- 
 after the application of fresh sawdust. 8 en drain ' thls P roduct ma Y then b e sold 
 There is also some evidence that fresh immediately or after composting. The 
 sawdust may contain some toxic chem- species most frequently sold is redwood; 
 icals, making a composting or leaching where other species are sold, they are gen- 
 period desirable. erally kept separate. 
 
 [16] 
 
Investment Marketing 
 
 No information was available on estab- Almost all shipments are made by truck, 
 lished plants. Required are a method of Most frequent are bulk sales at the mill 
 collection of the sawdust, a simple screen, and the operator has no further interest 
 and adequate space to stockpile large in the distribution system. Some mills con- 
 amounts because sales are seasonal. A sys- sign their production to a processor who 
 tern for truck loading of bulk sales is handles the distribution but most sell on 
 needed, and one for sacking if package a first-come-first-serve basis. Uusally bulk 
 sales are planned. Metering and mixing sales are marketed through landscape con- 
 equipment is necessary for the addition tractors and nurseries; package sales 
 of chemicals. through nurseries and chain stores. 
 
 References 
 
 Allison, F. E., and M. S. Anderson 
 
 1951. The use of sawdust for mulches and soil improvement. Washington, D. C, 
 USDACir.891. 
 
 Allison, F. E., R. M. Murphy, and C. J. Klein 
 
 1963. Nitrogen requirements for the decomposition of various kinds of finely ground 
 woods in soil. Soil Sci. 97(3) : 187-90. 
 
 Anderson, M. S. 
 
 1957. Sawdust and other natural organisms for turf establishment and soil improve- 
 ment. Washington, D. C, USDA Agr. Res. Serv. ARS 41-18. 
 
 Bollen, W. B., and D. W. Glennie 
 
 1961. Sawdust, bark and other wood waste for soil conditioning and mulching. For. 
 Prod. Jour. 11(1) : 38-46. 
 Gessel, Stanley P. 
 
 1959. Composts and mulches from wood waste. Univ. of Washington Inst, of For. 
 Prod. Cir. 33. 
 Mclntyre, Arthur C. 
 
 1952. Wood chips for the land. Washington, D. C, USDA Soil Cons. Serv. Leaf. 323. 
 Richards, S. J., J. E. Warneke, A. W. Marsh, and F. D. Aljibury 
 
 1964. Physical properties of soil mixes. Soil Sci. 98(2) : 129-32. 
 Wilde, S. A. 
 
 1958. Marketable sawdust composts: Their preparation and fertilizing value. For. 
 Prod. Jour. 8(11) : 323-26. 
 
 CHARCOAL 
 
 The consumption of charcoal is rising steadily, but the selling price has declined and 
 only about 40 per cent of the production capacity was used in 1961, the latest year for 
 which data are available. About 3V3 units of wood are required to produce 1 ton of 
 charcoal from softwoods. At the current price of pulp chips, raw material costs would 
 be $20 to $21 per ton of product; conversion costs would add about $10 to $14 per 
 ton depending upon equipment. With a selling price of $35 per ton for charcoal fines, 
 it can easily be seen that charcoal producers cannot compete with pulp mills for raw 
 material. 
 
 Charcoal production may be attractive, however, as a use for residues unsuitable 
 for pulp production. This includes bark, unbarked wood, sawdust, and shavings. Using 
 this type of material, a charcoal operation could approximately break even at a $7 per 
 unit raw material price. If combined with a briquetting plant, an efficient overall opera- 
 tion should be profitable. Briquetting costs run about $20 to $30 per ton and the selling 
 price of briquettes is about $75 to $90 per ton. 
 
 Many charcoal producers are inadequately financed, and therefore unable to in- 
 
 [17] 
 
ventory production through the winter for sale in the spring. A firm not handicapped 
 in this fashion would have a considerable advantage over competitors. Automated 
 continuous charcoal production would seem an attractive possibility because produc- 
 tion is heavily concentrated in the eastern part of the country, markets are local, and 
 batch-type operations are mostly rather inefficient. The disadvantages are the large raw 
 material requirements and the fact that charcoal production cannot compete with pulp 
 production for raw material. 
 
 Charcoal is one of the oldest of manu- 
 factured products. It has been used both 
 as domestic fuel and in industry. Industrial 
 uses have become less important and 
 domestic uses, particularly for outdoor 
 cooking, now dominate the market. The 
 industrial uses that have remained import- 
 ant are primarily the various applications 
 of activated charcoal for purification pur- 
 poses. Production statistics and import-ex- 
 port trade are presented in Anon. ( 1963) , 
 tables 1 and 2. Price information is pre- 
 sented in table 1 1 of the same publication. 
 The data indicate that 98 per cent of the 
 charcoal is produced east of the Rocky 
 Mountains. Consumption figures are not 
 available but because of the recreational 
 activity in a mild climate it seems logical 
 to expect that California's per capita con- 
 sumption, at least for domestic purposes, 
 would be above the national average. 
 Much of the charcoal consumed in Cali- 
 fornia, therefore, is imported from the 
 East. 
 
 At the present time, most charcoal is 
 produced from cordwood either in batch- 
 type kilns, where the products of combus- 
 tion of the charge itself are used to supply 
 the heat for carbonization after an initial 
 start-up period, or by batch-type retort 
 where the heat of carbonization is pro- 
 vided by an external source. Recently, a 
 number of pieces of equipment for con- 
 tinuous operation, using sawmill residues, 
 have been developed. Only the continuous 
 process is considered in this report. 
 
 Hardwood charcoal is preferred but 
 softwood charcoal is saleable. 
 
 Properties and uses 
 
 Industry uses about 10 per cent of char- 
 coal production, mostly for metallurgy 
 and purification processes such as sugar 
 refining. California consumption of wood 
 charcoal for industrial purposes in 1961 
 was negligible. 
 
 The principal quality requirement for 
 
 most charcoal is that it contain more than 
 80 per cent of fixed carbon. Activated 
 carbon usually has fewer impurities and a 
 greater percentage of fixed carbon, and 
 has been treated to increase its adsorptive 
 capability. 
 
 Raw material requirements 
 
 The minimum operating capacity for a 
 continuous charcoal operation seems to be 
 about 10 tons of charcoal per day. With a 
 recovery of about 20 to 25 per cent from 
 softwood, this means a daily intake of 
 from 40 to 50 tons of wood residues. Units 
 of several times this capacity are available. 
 Generally, all residues from bark and 
 chunks to sawdust and shavings can be 
 processed but the larger pieces must first 
 be hogged. 
 
 Manufacture 
 
 The first step in charcoal production by 
 a continuous process is the reduction of 
 the residues to fines, usually with a maxi- 
 mum diameter of W to %" in the least 
 dimension. The residues are introduced 
 through an airlock into the carbonizing 
 chamber which is maintained at a tem- 
 perature of about 700°-1000° F. The off- 
 gases are usually recovered to heat the 
 process after an initial start-up period but 
 they may be flared and natural gas used 
 under some circumstaces. Excess off-gases 
 are normally flared but could be used as 
 fuel in a boiler. The wood is reduced to 
 charcoal for about 15 minutes to Vi hour 
 and is ejected from the carbonizing cham- 
 ber through a second airlock and cooled. 
 
 Capital investment 
 
 Investment data for two continuous retorts 
 processing hogged wood are given below. 
 The third, processing mill ends on a batch 
 basis, is included for comparison. 
 
 These figures were supplied by the equip- 
 ment manufacturer in each case. In gen- 
 eral, it appears that a minimum of $125,- 
 
 [18] 
 
Comparison of Investment Costs 
 
 
 Continuous 
 
 Continuous 
 
 Batch 
 
 Item 
 
 10 tons/day 
 
 50 tons/day 
 
 20 tons/day 
 
 Buildings 
 
 $40,000 
 80,000 
 10,000 
 
 $100,000 
 
 325,000 
 
 25,000 
 
 $30,000 
 
 
 80,000 
 
 
 10,000 
 
 
 
 
 $130,000 
 
 $450,000 
 
 $120,000 
 
 000 plus land, utilities, and working capi- 
 tal is required for any continuous charcoal 
 operation. 
 
 Marketing 
 
 From a practical standpoint, the choices in 
 marketing of the charcoal fines produced 
 by these plants are relatively limited. Fines 
 can be sold to an independent charcoal 
 briquetting plant or can be briquetted in 
 a captive plant. The reported price for 
 charcoal fines in California in 1963 was 
 between $30 and $35 per ton although 
 the U.S. Forest Service reported that the 
 delivered price at the briquetting plant in 
 California in 1961 was $44 per ton. 
 
 Charcoal briquetting 
 
 The increasing charcoal consumption in 
 the United States, mentioned earlier, is 
 essentially caused by the expansion of rec- 
 reational use of charcoal in the form of 
 briquettes. A single ownership of both 
 charcoal producing and briquetting facili- 
 ties enhances both operations. Therefore, 
 any charcoal producing installation should 
 
 be associated with a briquetting plant if at 
 
 all possible. 
 
 Raw material requirements — One ton 
 
 per hour appears to be the minimum 
 operating rate for an economical charcoal 
 briquetting plant. However, units with 2 
 to 3 tons capacity per hour appear to be 
 more common. 
 
 Manufacture — Briquettes are produced 
 by crushing the charcoal, usually by a 
 hammer mill, mixing it with starch and 
 water and forming in a press. The bri- 
 quettes then are dried and sacked. Com- 
 position of the mixture at the time of 
 pressing is about 73 parts charcoal, 4 parts 
 starch, and 23 parts water. 
 Capital investment — Estimates for sev- 
 eral briquetting plants, obtained from the 
 manufacturers, are given in the table 
 below, and include as many details as 
 were available. 
 
 Marketing — Most of the charcoal bri- 
 quettes produced are sold to jobbers for 
 distribution. A large amount is sold to 
 chain-type retail outlets and a limited per- 
 centage directly to local stores. 
 
 Briquette Plant — Investment in Addition to Freight, Land and Utilities 
 
 
 
 
 Estimated costs 
 
 
 Item 
 
 Manufacturer 1 
 
 Manufacturer 2 
 
 Manufacturer 3 
 
 Manufacturer 4 
 
 
 2 tons/hr 
 
 2 tons/hr 
 
 2 tons/hr 
 
 1-1>£ tons/hr 
 
 2-3 tons/hr 
 
 Equipment 
 
 $75,000 
 46,500 
 72.500 
 19,500 
 
 $62,000 
 
 $ 
 
 $123,000 
 81,000 
 
 $167,000 
 
 Conveyors, hoppers, bins, etc 
 
 
 Buildings 
 
 Contingencies 
 
 138,000 
 
 
 
 Total 
 
 $213,500 
 
 $62,000 
 
 $275,000 
 
 $204,000 
 
 $305 000 
 
 
 
 References 
 
 Anonymous 
 
 1957. Charcoal production in the United States. Washington, D. C. 
 Serv. Div. of For. Econ. Res. 14 pp. 
 
 USDA For. 
 
 19] 
 
1961. Charcoal production, marketing, and use. Madison, Wise, U. S. For. Prod. 
 Lab. Rept. 2213. 
 
 1961. Charcoal briquettes sales. Raleigh, N. C, Aeroglide Corp. Inf. Bui. 402. 
 
 1962. Charcoal. FAO of the UN, Rome, Occasional Paper 2. 
 
 1963. Charcoal and charcoal briquette production in the United States, 1961. Wash- 
 ington, D. C, USDA For. Serv. Div. of For. Econ. and Marktg. Res. 33 pp. 
 
 Beglinger, E. 
 
 1952. Charcoal production. Madison, Wise, U. S. For. Prod. Lab. FPL No. R1666- 
 11. 
 
 Hempf , F. E. 
 
 1957. Production and sale of charcoal in the Northeast. Upper Darby, Pa., North- 
 eastern For. Exp. Sta. Paper 100. 
 
 Jarvis, J. R. 
 
 1960. The wood charcoal industry in the state of Missouri. Columbia, Mo., Univ. of 
 Missouri Eng. Ser. Bui. 48. 
 
 Kasile, J. 
 
 1962. Wood charcoal production in California for 1961. Berkeley, Calif., Pac. South- 
 west For. and Range Exp. Sta. Res. Note 210. 
 Keppler, W. E., and W. T. Huxter 
 
 1962. Feasibility guide for charcoal briquetting plant. Raleigh, N.C., Wood Prod. 
 Ext. Sect., Sch. of For., North Carolina State College. 
 Pritchard, W. M. 
 
 1960. A simplified charcoal retort. For. Prod. Jour. 10(12) : 640-41. 
 
 1961. Simplified batch retort permits economical charcoal production. Hitchcock's 
 Wood Working Digest 63(3) : 48-50. 
 
 Simmons, F. D. 
 
 1957. Guides to manufacturing and marketing charcoal in the northeastern states. 
 Upper Darby, Pa., Northeastern For. Exp. Sta. Paper 95. 
 Warner, John R., and W. B. Lord 
 
 1957. The market for domestic charcoal in Wisconsin. St. Paul, Minn., Lake States 
 For. Exp. Sta. Paper 46. 
 
 MISCELLANEOUS PRODUCTS 
 
 Sweeping compounds are feasible, current needs are probably 
 
 The manufacture of sweeping compounds supplied from local sources in each market 
 
 Wood shavings 
 
 from sawdust presents a limited oppor- area, 
 tunity for sawdust utilization. Ingredients 
 usually are sawdust, paraffin oil, powdered 
 
 wax, salt, sand, and fragrance and coloring A g° od market for wood shavings exists, 
 
 materials as desired. Proportions vary but largely as poultry and livestock litter. Pine 
 
 one formula uses 30 parts sawdust, 1 part and tru e fir species are preferred in this 
 
 paraffin oil, 1 part salt, 10 parts sand, and us e, and incense cedar is unacceptable, 
 
 a small amount of powdered wax. Shavings are normally baled, but occasion- 
 
 The oil and wax are generally heated all Y ma Y be sold in bul k- 
 and the dry ingredients added to it. Mixing . 
 
 is done in a tumbling drum similar to a Bne l"etted wood 
 
 concretemixer. Compressed wood fines fuel logs have 
 
 No study of markets was made. Pre- been produced for many years and an 
 
 sumably marketing would be through established market exists. Each machine 
 
 janitorial supply houses or jobbers. Since for the production of the only important 
 
 investment is limited and small operations product of this type requires approxi- 
 
 [20] 
 
mately 12 tons of kiln-dried residues per 
 day. Mill sales price of this product in 
 Humboldt County in the fall of 1963 was 
 $14 per ton. Markets are largely in metro- 
 politan areas, and distance to markets is 
 important. Merchandising is a factor that 
 is not very well exploited by most current 
 producers. 
 
 A potential market, just beginning to be 
 exploited, is for recreational use. This mar- 
 ket could perhaps be best served by 
 smaller production units located in the 
 market area. A process which seems to 
 have several advantages for this approach 
 has recently been developed by the British 
 Columbia Research Council. Their "Fuel 
 Log Process" uses wet sawdust as a raw 
 material to produce a log which does not 
 disintegrate on outside storage. 
 
 The log making machine sells for about 
 $5,000 including royalties and can pro- 
 duce about 1,300 pounds of logs in eight 
 hours. This should facilitate pilot or small 
 plant operations although the most effici- 
 
 References 
 
 ent operation would include a battery of 
 machines. Production costs have been 
 estimated at $20 per ton. This means that 
 in order for the operation to compete with 
 other processes, a special market situation 
 must exist. It must be possible to minimize 
 both transportation and sales costs. Areas 
 with both summer and winter recreation 
 and adjacent to the producer, such as near 
 Lake Tahoe and Mt. Shasta, might meet 
 these requirements to a high degree. 
 
 It has also been reported that a wafer- 
 ing machine developed for processing 
 cattle fodder is suitable for use on wood 
 fines. Cubes or briquettes produced by 
 this method might also be saleable to the 
 recreational market and compete directly 
 with charcoal, but actual saleability and 
 production problems and costs have not 
 been evaluated by the author. 
 
 Use of these products as a heat source 
 for the protection of crops has been tested 
 in a limited way with encouraging results 
 but the use has not been developed. 
 
 Anonymous 
 
 1962. Sawdust floor-sweeping compounds. Madison, Wise, U. S. For. Prod. Lab. 
 
 FPL No. 1666-14. 3 pp. 
 1964. Fuel log process. Vancouver, B. C, British Columbia Res. Council. 6 pp. 
 Ivory, E. P. 
 
 1956. Reducing sawmill waste 90 per cent in six years. For. Prod. Jour. 6(8) : 279-81. 
 Reineke, L. H. 
 
 1955. Briquets from wood waste. Madison, Wise, U. S. For. Prod. Lab. FPL No. 
 1666-13. 7 pp. 
 
 APPENDIX: RESIDUE ESTIMATION 
 
 A firm contemplating the use of its proc- 
 essing residues must first determine and 
 classify these residues by type and volume. 
 This can be done in a number of ways. 
 Estimates may be made from averages re- 
 ported by industry or from studies in vary- 
 ing detail made at a particular operation. 
 The outline of a very intensive study of 
 residues developed at a particular opera- 
 tion, based on a materials balance, is re- 
 ported by Shelton (1954). At the other 
 extreme is the sampling of the material in 
 the burner conveyor for a short period of 
 time, then scaling up this sample to esti- 
 mate total production. The materials bal- 
 
 ance approach requires more manpower 
 than may be available to most operators. 
 On the other hand, sampling and the use 
 of industry averages may provide insuffi- 
 cient or erroneous answers. Several refer- 
 ences on residue surveys are listed on page 
 26. 
 
 The procedure described here lies be- 
 tween these extremes. It is well within the 
 capability of any firm, and yet it provides 
 accurate information in detail adequate 
 for sound planning of most ventures. This 
 study was made of a firm in the California 
 Pine Region operating two sawmills and 
 a remanufacturing plant. 
 
 [21] 
 
Table A-l. Log Size Frequency Distribution for the 
 Three-month Sample Period 
 
 Bd ft class 
 
 Diam. 
 
 class 
 
 (inches) 
 
 Number of logs 
 
 Bd ft class 
 midpoint 
 
 Diam. 
 
 class 
 
 (inches) 
 
 Number of logs 
 
 midpoint 
 
 Mill A 
 
 Mill B 
 
 Mill A 
 
 Mill B 
 
 25 
 
 8 
 9 
 
 5 
 
 30 
 
 4 
 9 
 
 725 
 
 31 
 32 
 
 35 
 32 
 
 37 
 36 
 
 75 
 
 10 
 11 
 12 
 13 
 
 56 
 72 
 90 
 98 
 
 14 
 18 
 22 
 25 
 
 775 
 
 33 
 
 29 
 
 34 
 
 
 825 
 
 34 
 
 26 
 
 33 
 
 
 875 
 
 35 
 
 23 
 
 31 
 
 
 950 
 
 36 
 
 20 
 
 30 
 
 125 
 
 14 
 15 
 
 103 
 103 
 
 29 
 32 
 
 1050 
 
 37 
 38 
 
 18 
 16 
 
 28 
 
 26 
 
 175 
 
 16 
 17 
 
 99 
 95 
 
 35 
 
 38 
 
 1150 
 
 39 
 
 15 
 
 24 
 
 
 1250 
 
 40 
 
 13 
 
 22 
 
 225 
 
 18 
 19 
 
 91 
 86 
 
 41 
 43 
 
 1350 
 
 41 
 42 
 
 12 
 
 10 
 
 20 
 15 
 
 275 
 
 20 
 21 
 
 81 
 
 77 
 
 45 
 47 
 
 1450 
 
 43 
 
 44 
 
 9 
 
 7 
 
 13 
 
 10 
 
 325 
 
 22 
 
 72 
 
 47 
 
 1550 
 
 45 
 46 
 
 6 
 5 
 
 8 
 
 375 
 
 23 
 
 67 
 
 46 
 
 6 
 
 425 
 
 24 
 
 62 
 
 45 
 
 1650 
 
 47 
 
 4 
 
 5 
 
 475 
 
 25 
 
 58 
 
 44 
 
 1750 
 
 48 
 
 3 
 
 5 
 
 525 
 
 26 
 27 
 
 54 
 50 
 
 43 
 42 
 
 1850 
 
 49 
 50 
 
 3 
 2 
 
 4 
 3 
 
 575 
 
 28 
 
 46 
 
 40 
 
 1950 
 
 51 
 
 1 
 
 2 
 
 625 
 
 29 
 
 43 
 
 39 
 
 2050 
 
 52 
 
 1 
 
 1 
 
 675 
 
 30 
 
 39 
 
 38 
 
 
 
 
 
 Procedure 
 
 Sawmills — Chippable material available 
 was estimated at each sawmill. A sample 
 of logs was measured and followed 
 through the headrig. Breakdown pattern 
 for each log was recorded and slab volume 
 determined, assuming a round cross-sec- 
 tion but taking taper into account. The 
 volume of individual edging pieces was 
 estimated and an average value applied to 
 each board edged from the sample logs. 
 Trimming data were developed from saw 
 spacings and from a sampling of grade 
 trimming practices. Trim residues were 
 assumed to be constant for all log diame- 
 ters since trimming for grade in the con- 
 ventional sense did not appear to be prac- 
 
 ticed. Bark volume was estimated from 
 bark thickness and log diameter and 
 length data. Sawdust volume was not esti- 
 mated but this could be done from the 
 available data. 
 
 Remanufacturing plant — Total chippa- 
 ble residues were computed on the basis 
 of past pulpwood shipments plus an esti- 
 mated 5 per cent additional now being 
 shunted to the burner and the boiler. A 
 rough estimate only was made of fine resi- 
 dues at the remanufacturing plant because 
 fine residues are less promising than coarse 
 residues for the manufacture of useful 
 products. The estimate was made on the 
 basis of computed current consumption 
 for steam production. 
 
 [22 
 
Sawmill Residues Generated on a Daily Cut of 75 MBM Log Scale 
 
 Item 
 
 Mill A 
 
 Chippable wood 
 
 Bark 
 
 Mill B 
 
 Chippable wood 
 
 Bark 
 
 Cu ft/MBM 
 
 Cu ft/day 
 
 Cu ft/240-day year 
 
 36.9 
 21.4 
 
 31.1 
 20.0 
 
 2767.5 
 1605.0 
 
 2332.5 
 1500.0 
 
 664,200 
 385,200 
 
 559,800 
 360,000 
 
 * Sawdust not included. 
 
 Results 
 
 The amount of chippable residues avail- 
 able at the sawmills depends on the spe- 
 cies, size, and quality of the logs being cut. 
 Log data were available for only a three- 
 month period of 1963; they are presented 
 in table A-l, giving log size frequency dis- 
 tribution. Figure 5 shows the relationship 
 
 between log diameter and chippable ma- 
 terial produced per MBM log scale. The 
 similar relationship for bark, which did 
 not vary noticeably between mills, is 
 given in figure 6. Table A-2 presents the 
 effect of differences in log diameter distri- 
 butions, showing chippable and bark 
 residual per MBM as affected by log 
 
 Table A-2. Cubic Feet of Residual per MBM 
 
 as Affected by Log Diameter 
 
 Bdft 
 class 
 
 Diam. 
 
 class 
 
 (inches) 
 
 Chippable wood 
 
 Bark, both 
 mills 
 
 Bdft 
 
 class 
 
 midpoint 
 
 Diam. 
 
 class 
 
 (inches) 
 
 Chippable wood 
 
 Bark, both 
 
 midpoint 
 
 Mill A 
 
 Mill B 
 
 Mill A 
 
 Mill B 
 
 mills 
 
 25 
 
 8 
 9 
 
 
 
 33.0 
 30.2 
 
 725 
 
 31 
 32 
 
 23.0 
 22.2 
 
 28.7 
 27.8 
 
 17.1 
 17.1 
 
 75 
 
 10 
 11 
 12 
 13 
 
 78.5 
 71.0 
 
 
 27.7 
 25.6 
 23.6 
 20.8 
 
 775 
 
 33 
 
 21.5 
 
 26.9 
 
 17.1 
 
 
 825 
 
 34 
 
 21.0 
 
 26.1 
 
 17.1 
 
 
 875 
 
 35 
 
 20.6 
 
 25.4 
 
 17.1 
 
 
 950 
 
 36 
 
 20.1 
 
 24.7 
 
 17.1 
 
 125 
 
 14 
 15 
 
 64.3 
 58.5 
 
 74.2 
 
 20.3 
 19.0 
 
 1050 
 
 37 
 38 
 
 19.7 
 19.4 
 
 24.0 
 23.5 
 
 17.1 
 17.1 
 
 175 
 
 16 
 17 
 
 53.8 
 49.3 
 
 66.8 
 61.0 
 
 17.7 
 16.6 
 
 1150 
 
 39 
 
 19.1 
 
 22.8 
 
 17.1 
 
 
 1250 
 
 40 
 
 18.8 
 
 22.3 
 
 17.1 
 
 225 
 
 18 
 19 
 
 46.0 
 42.2 
 
 55.6 
 51.4 
 
 15.8 
 15.2 
 
 1350 
 
 41 
 42 
 
 18.6 
 18.3 
 
 21.7 
 21.3 
 
 17.1 
 
 17.1 
 
 275 
 
 20 
 21 
 
 39.2 
 36.6 
 
 47.6 
 44.5 
 
 15.0 
 14.9 
 
 1450 
 
 43 
 44 
 
 18.2 
 18.1 
 
 20.8 
 20 4 
 
 17.1 
 17.1 
 
 325 
 
 22 
 
 34.3 
 
 41.7 
 
 15.0 
 
 1550 
 
 45 
 46 
 
 18.0 
 
 17.9 
 
 20.0 
 19.5 
 
 17.1 
 
 375 
 
 23 
 
 32.2 
 
 39.6 
 
 15.3 
 
 17.1 
 
 425 
 
 24 
 
 30.5 
 
 37.9 
 
 15.7 
 
 1650 
 
 47 
 
 17.8 
 
 19.3 
 
 17.1 
 
 475 
 
 25 
 
 28.8 
 
 36.2 
 
 16.2 
 
 1750 
 
 48 
 
 17.7 
 
 19.0 
 
 17.1 
 
 525 
 
 26 
 27 
 
 27.5 
 26.7 
 
 34.7 
 33.2 
 
 16.5 
 16.8 
 
 1850 
 
 49 
 50 
 
 17.6 
 17.5 
 
 18.7 
 18.4 
 
 17.1 
 17.1 
 
 575 
 
 28 
 
 25.5 
 
 31.9 
 
 17.0 
 
 1950 
 
 51 
 
 17.4 
 
 18 
 
 17.1 
 
 625 
 
 29 
 
 24.6 
 
 30.8 
 
 17.0 
 
 2050 
 
 52 
 
 17.3 
 
 17.7 
 
 17.1 
 
 675 
 
 30 
 
 23.7 
 
 29.6 
 
 17.1 
 
 
 
 
 
 
 [23] 
 
90 
 
 
 
 l\ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 \ 
 
 i 
 
 
 
 
 
 
 
 
 
 
 CO 
 
 * 60 
 
 
 
 \ 
 
 \ 
 
 
 
 
 
 
 
 
 
 
 r 
 
 3 50 
 
 
 
 
 \\ 
 
 
 
 
 
 
 
 
 
 
 72 
 
 
 
 w 
 
 0> 
 
 _Q 40 
 O 
 
 Q. 
 Q. 
 
 JC 
 
 U 30 
 
 
 
 
 \ > 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Mill B 
 
 
 
 
 
 
 
 
 
 
 
 
 Mill A 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Diameter (inches) 
 
 Fig. 5. Cubic feet of chippable wood residual per MBM log scale from logs of various 
 diameters. 
 
 diameter. If a significant shift in diameters 
 of logs were to occur, the amount of 
 residues anticipated to be available should 
 be adjusted according to the table. 
 
 A daily cut of 75 MBM/day would pro- 
 duce the volumes of residues shown in the 
 table "Cubic Feet of Residual per MBM 
 as Affected by Log Diameter" on page 23. 
 
 45 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 30 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 15 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 2 
 
 
 
 3 
 
 
 
 4 
 
 
 
 5 
 
 
 
 G 
 
 
 
 Diameter (inches) 
 
 Fig. 6. Cubic feet of bark residual per MBM log scale from logs of various diameters (both 
 mills A and B). 
 
 [24] 
 
CO 
 
 ^ 2000 
 
 Q- .9- 
 
 1i 
 
 -Q 
 
 E 
 
 3 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 _l: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / i 
 
 *. 
 
 
 
 
 
 
 
 
 
 
 
 
 / / 
 / 
 
 "N 
 
 Lumber and box 
 
 
 
 ^ / 
 
 \ 
 
 
 '^ 
 
 
 > 
 / 
 
 
 
 
 / 
 / 
 
 
 \ 
 
 N 
 
 / 
 
 / 
 / 
 
 
 
 
 / 
 
 > 
 
 s 
 
 • 
 • 
 
 ' 
 
 
 
 
 r 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1234 12341234 
 
 1960 1961 1962 
 
 Fig. 7. Shipment of products — remanufacturing plant (quarterly averages). 
 
 REMANUFACTURING RESIDUES 
 
 Figure 7 presents the pulpwood shipments 
 from the plants and the total lumber and 
 box shipments for the past three years. 
 There appears to be a fair degree of cor- 
 relation between these curves. On this 
 
 basis, a ratio of 0.147 ton, or 294 pounds, 
 of chippable wood produced per MBM 
 of wood products shipped was estab- 
 lished. 3 Fine residues (sawdust and shav- 
 ings), now used for fuel, were estimated 
 to total 0. 154 ton per MBM. 
 
 Remanufacturing plant residues generated on a daily 
 production of 200 MBM 
 
 Per MBM Per day Per 240-day year 
 
 Chippable wood . . . 19.7 cu ft 3944.0 cu ft 946,560 cu ft 
 
 Sawdust & shavings . . 308 lbs 61,600 lbs 18,784,000 lbs 
 
 Discussion 
 
 The residues have not been separated by 
 species. The species composition would be 
 approximately related to the ratio of spe- 
 cies processed for lumber. The fluctua- 
 tions in species processed in the past are 
 given in figure 8. The utility and problems 
 connected with the use of different species 
 vary, depending on the product made. If 
 
 8 There are approximately 3,000 pounds of 
 wood material per 200 cu ft unit of hogged 
 wood and approximately 1,600 pounds per 
 cord unit of trim ends. 
 
 a utilization plan is adopted which is sensi- 
 tive to species differences, considerable 
 care will need to be exercised in planning 
 of timber purchases and logging opera- 
 tions to maintain the desired balance. As 
 is shown in the table giving chippable and 
 bark residual per MBM as affected by log 
 diameter, a change in log diameters proc- 
 essed significantly affects the volume of 
 residues available. If a shift does occur in 
 log diameters processed, residue projec- 
 tions should be adjusted in accordance 
 with this table. 
 
 [25] 
 
^ 4000 
 
 CO 
 
 1 
 
 c 
 
 0) 
 
 E 3000 
 
 Q. 
 
 IE 
 
 CO 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Total ■■ White f.r 
 
 
 
 
 
 
 1 
 
 1 
 
 
 
 
 
 
 - Pine 
 
 __ Douglas-fir 
 
 
 
 
 
 / 
 1 
 1 
 
 1 
 
 1 
 \ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 *.— - 
 
 I 
 
 t 
 
 r— - 
 f 
 
 r \ i 
 
 \ t 
 
 LA 
 
 
 
 
 
 
 ft 
 / \ 
 
 
 
 
 / 
 
 / 
 
 1 
 
 
 
 1 
 1 
 1 
 
 s 
 
 i 
 / 
 
 V 
 
 
 i 
 
 
 
 
 
 1 
 
 
 / 
 
 "■^ 
 
 
 
 
 \ 
 
 1 
 
 f 
 
 j 
 
 [ 
 
 V^ 
 
 
 
 
 
 > 
 
 /\ 
 
 7~~-zfi 
 
 
 
 
 
 
 /V, 
 
 l7 
 
 £ 
 
 \^ 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 A 
 
 /T 
 
 *H 
 
 \J 
 
 V 
 
 
 
 
 
 
 
 
 
 
 
 .---'-' 
 
 \ / 
 
 • 
 
 / 
 
 \ 
 
 
 
 
 
 
 
 /\ \ 
 
 
 
 
 
 .^■^ 
 
 
 k 
 
 * 
 
 y\ 
 
 
 
 
 
 
 
 
 / \ 
 
 
 '^V, 
 
 
 
 
 
 w \ 
 
 / 
 t 
 
 _^~ x 
 
 ^f. X 
 
 
 
 
 
 F-b May Aug Nov Feb May Aug Nov F«b May Aug Nov Feb May Aug Nov 
 I960 1961 1962 1963 
 
 Fig. 8. Monthly lumber shipments by species — remanufacturing plant. 
 
 Selected bibliography on residue surveys 
 
 Anonymous 
 
 1957. Conversion factors for Pacific Northwest forest products. Univ. of Washington 
 Inst, of For. Prod. 
 Batori, S. M. 
 
 1957. Wood equivalents — logs to boards, plywoods, and products from residuals. 
 Amer. Soc. Mech. Engrs. Paper 57-SA-88. 8 pp. 
 Carpenter, R. D. 
 
 1950. Amount of chippable waste at Southern Pine sawmills. New Orleans, La., 
 Southern For. Exp. Sta., Occasional Paper 115. 
 Corder, S. E. 
 
 1964. Mill residues in Jackson and Josephine counties in 1962. Oregon State Univ. 
 For. Res. Lab. Inf. Cir. 19. 
 May, R. H., and L. N. Ericksen 
 
 1955. Wood residue from primary wood-using industries in California. Calif. For. & 
 Range Exp. Sta. Tech. Paper 13. 
 Sarvis, J. C. 
 
 1959. Bark utilization study. Portland, Ore., West Pine Assn. Res. Note 7.221. 1 1 pp. 
 Shelton, N. T. 
 
 1954. Chip yield and materials balance as related to log size in the California pine 
 and fir region. For. Prod. Jour. 6(8) : 281-84. 
 
 [26] 
 
To simplify the information, it is sometimes necessary to use trade names of products or equip- 
 ment. No endorsement of named products is intended nor is criticism implied of similar products 
 not mentioned. 
 
 7 1 / 2 m-10,'65(F5045)J.F.