TANNING MATERL^LS 75 



required. The above figures of production, cost and yield are largely 

 taken from Benson. ^ 



TANBARK OAK 



Tanbark oak {Quercus densiflora) is a native of southern Oregon, and 

 of California, where the harvesting of tanning bark has been an important 

 industry for many years. Commercial tanning has been in progress on 

 the Pacific Coast ever since the gold wave of 1849-1850. As early as 

 1852 Sonoma County had a tannery producing $30,000 worth of leather 

 per year, and by 1859 there were 29 tanneries. In the ten-year period 

 1881 to 1890, 240,000 cords were produced in California. Excellent 

 prices have been obtained for this bark, which contains an exceedingly 

 high tannin content — about 29 per cent. 



The tree ranges from southwestern Oregon along the coast range to 

 Santa Barbara in southern California. It is commonly associated in 

 its native habitat with the redwoods. 



The Santa Cruz district produces the largest present supply, and the 

 source of supply is being rapidly exhausted. It is estimated that in 1900 

 about 75 per cent of the total available supply had been cut and peeled 

 for the bark. Some second growth is appearing, but it is exceedingly 

 slow in its development. A great deal of the oak has been cut for the 

 bark alone. 



The largest remaining available supply is now foimd in northern 

 Mendocino and Humboldt Counties. The relative inaccessibility of 

 many of these forests, and the consequent long haul involved has been an 

 important deterrent factor in preventing the cutting of a large portion 

 of the remaining supply. It is estimated that the total remaining stand 

 of tanbark is 1,425,000 cords, which, at the present rate of cutting is 

 estimated to last about forty to forty-five years. The average yield is 

 about 200 to 300 cords " per claim " of 160 acres, or from ij to 2I cords 

 per acre. In estimating the yield it is said that six average trees will make 

 a cord of bark in the most important producing sections. The peeling 

 season is from May 20th to August loth, but varies with the weather, 

 altitude, temperature, etc. This oak is extremely sensitive to heat and 

 cold, and a cold spring will delay the opening of the peeUng season, and 

 cold weather will cause the bark to adhere closely to the tree. About 

 one-half a day is required for two men to peel a large tree. The peelers 

 never begin on a tree unless they can finish peeling during the day, as the 



• From " By-Products of the Lumber Industry," by H. K. Benson, Department of 

 Commerce, 1916. 



