Timbers

Resorcinol is to phenol as melamine is to urea. Resorcinol—formaldehyde (RF) is very expensive, produces dark and waterproof gluelines, but will cure at room temperature. As with melamine and urea, resorcinol is often combined with phenol to produce phenol—resorcinol—formaldehyde (PRF) adhesives, thus producing an exceUent adhesive with some of the economy of phenol. These adhesives are the mainstay of the laminated timber industry which generally requites a room-temperature cure with durable, waterproof gluelines. 

Chemical iajections iato piae trees have been reported to have stimulatory effects on the natural production of resias and terpenes and may result ia high yields of these valuable chemicals. Combiaed oleoresin—timber production ia mixed stands of piae and timber trees is under development, and it appears that when short-rotation forestry is used, the yields of energy products and timber can be substantially higher than the yields from separate operations. 

Lindane is used predominately as a seed dressing and soil insecticide, for the control of ectoparasites of humans and domestic animals, for the control of locusts and grasshoppers, and as a residual spray to control the Anopheles vectors of malaria. Because of its relatively high volatility it is useful to control wood-boring insects of timber, fmit trees, and ornamental plants. The mode of action is not well understood but is thought to be competitive blocking of the y-aminobutyric acid (GABA) transmitter of synaptic nerve transmission. 

Specifications. Tar bulk products are covered by both national specifications and those formulated by the user. For instance, creosote for timber preservation is covered by the American Wood Preserving Association Standards (AWPA) and ASTM D350. 

In the United States creosote specification AWPA PI/89 is intended for the treatment of timber for land and fresh-water use, and the heavier grade AWPA P13/89 for the preservation of marine piling and timber. In the United Kingdom a British Standard Specification, BS. 144/90, Part 1, specifies three grades of creosote two for pressure impregnation and one for bmshing appHcation. The standards of the West European Institute for Wood Preservation (WEI) are often used in Europe. 

Creosote oils are by far the most widely used timber preservatives (see Wood). This use dates back to 1850. Eor the treatment of railway ties and marine pilings, the BetheU or fliU-ceU process is preferred. The timber to be treated is charged to a pressure cylinder, which is evacuated to extract the air from the wood ceUs. The cylinder is then filled with hot creosote and the pressure increased to 0.8—1 MPa (ca 8—10 atm) to force the oil into the ceUs. 

When uptake of the oil has ceased, residual creosote is drained from the cylinder and the treated timber is briefly subjected to a vacuum before discharge. 

Timber-preservation creosotes are mainly blends of wash oil, strained anthracene oil, and heavy oil having minor amounts of oils boiling in the 200—250°C range. Coal-tar creosote is also a feedstock for carbon black manufacture (see Carbon, carbon black). Almost any blend of tar oils is suitable for this purpose, but the heavier oils are preferred. Other smaller markets for creosote were for fluxing coal tar, pitch, and bitumen in the manufacture of road binders and for the production of horticultural winter wash oils and disinfectant emulsions. 

Primitive people very likely encountered vinegar-like Hquids in hoUows in rocks or downed timber into which berries or fmit had fallen. Wild yeasts and bacteria would convert the natural sugars to alcohol and acetic acid. Later, when eady peoples had learned to make wines and beers, they certainly would have found that these Hquids, unprotected from air, would turn to vinegar. One can postulate that such eady vinegars were frequendy sweet, because the fmit sugars would have been acted on simultaneously by both bacteria and yeast. Only since the middle 1800s has it been known that yeast and bacteria are the cause of fermentation and vinegar formation. 

Timber production in the United States is an important contributor to Gross Domestic Product (GDP). In 1991, timber-related activities in the United States generated -- 59,498 million (Table 7). It accounted for 2.2% of the goods and stmctures portion of GDP. Primary timber products production totaled 19,370 secondary timber-related products added 40,128 million of value in 1991. 

Table 7. Value of Primary and Secondary Timber Products and Gross Domestic Product (GDP) in the United States, 1991...

Table 8. Volume and Value of Roundwood Timber Products Harvested in the United States by Region, 1986 and 1991 ...

Total roundwood harvested increased by less than 300 million ft between 1986 and 1991 (Table 8). The value of all roundwood timber harvested in the United States in 1991 was estimated to be 19,370 million (Table 8). The value of roundwood timber is defined as the market value at local points of dehvery, ie, deUvered to a processing faciUty. 

Secondary Timber Products. Secondary timber products are products manufactured from primary timber products. Secondary products can be sold directly to the final consumer or can requite additional processing before reaching the final consumer. The wide diversity of products manufactured from primary timber products makes it difficult to precisely define secondary products. Lumber, for example, is clearly a secondary product because it is manufactured from roundwood and typically requites further processing before reaching its final use. Wooden furniture is considered a final product, not a secondary product because it is made from lumber or other secondary timber products. In general, products made from secondary timber products were not included in this analysis. 

Table 10 itemizes the specific four-digit Standard Industrial Classification (SIC) industries considered to be secondary timber products manufacturers. For more information on the SIC system, see Executive Office of the President, Office of Management and Budget (119). 

Table 10. Four-Digit SIC Secondary Timber-Related Manufacturing Industries in the United States ...

In 1991, timber-related secondary products manufacturing industries added an estimated 40,128 million of value to primary timber products (Table 11). Most of the timber-related value added (63%) originated in the paper and aUied products industry. The lumber and wood products industry added nearly 37% of total timber-related value added. Less than 1% was from chemicals and aUied products. 

Table 11. Value Added by Manufacture for Timber-Related Two-Digit SIC Industries by Region, 1991 ...

The South and North were the two largest timber-related secondary products manufacturing regions, adding 16,350 million (41%) and 15,549 million (30%) of value, respectively, in 1991 (Table 10). The Rocky Mountain and Pacific Coast regions combined added the remaining 20%. 

A.n A.naljsis of the Timber Situation in the Ended States 1989—2040, General Technical Report RM-199, U.S. Department of Agriculture, Eorest Service, Rocky Mountain Eorest and Range Experimental Station, Eort Collins, Colo., 1990. 

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