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to give actual loss figures. The reports showed that an uncertainty exists in the minds of many lumbermen as to what constitutes loss due to sap stain.

The interpretation of the questionnaire returns is admittedly difficult, due to the fact that it is practically impossible to apply a standard formula in arriving at how much the blue stain is costing the industry. There are many variables to be considered-the different opinions which the millmen hold with respect to blue-stain losses, the variation in species of wood, or in the climatic conditions, or in the type of industry, and in the methods of handling the lumber from log to finished product.

The mills which reported actual loss in their questionnaire returns gave production figures totaling 1,748,000,000 board feet and loss figures totaling $847,600. This would be at the rate of 48.5 cents per thousand board feet. It is obvious that such an estimate can not be accepted as absolutely final, because the questionnaire reports themselves indicated, as has been pointed out above, the difficulties which stood in the way of obtaining accurate figures at the mill. Personal observation and conversation with millmen all over the country have revealed cases where the degrade due to sap stain ran from $10 to $40 per thousand board feet in high-grade stock. Here the loss was recognized because the stock was so valuable that a fairly accurate record was kept of what happened to it, but such records are not kept of lower grade material. It is obvious, also, that the cost of dipping lumber to prevent blue stain is definitely referable to the action of the fungus. In other words, if the lumber were not actually reduced in value by blue stain, no one would go to the trouble or expense of dipping to prevent blue stain. Dipping costs vary tremendously, from 8 cents to as high as 50 cents per thousand board feet. The results of dipping are not always satisfactory; they do not always prevent a further degrade from blue stain and consequent depreciation in market value. When all of the angles of the question presented above have been considered, an estimated loss of 50 cents per thousand board feet of the species susceptible to blue stain appears to be very conservative. It is found that accurate cost accounting would show the loss to be considerably higher.

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What does this loss mean to the country as a whole? As near as we can figure it out there is a gross total of approximately 18,000,000,000 board feet of lumber cut from the susceptible species annually. Some of the species within this group are more susceptible than others, but if we apply the estimated-loss figure of 50 cents per thousand board feet to the production total we arrive at an annual loss of $9,000,000. If to this is added the estimates made by the sash and door industries of $1,000,000 and the estimates of other sap-stain losses and losses due to the brown stain in sugar and yellow pine amounting to $500,000, a grand total of $10,500,000 is obtained.

The above estimates do not include the losses due to staining and molding in the vehicle, basket and veneer, box and container, furniture and woodenware industries, nor in the export trade. The loss due to degrade caused by staining and molding of stock in transit is not included. An example of this type of loss (data furnished by

Reynolds, R. V., and Pierson, A. H., Lumber Cut of the United States, 1870-1920: U. S. Dept. of Agri. Bul 1119:1-62; April, 1923.

N. O. Howard) is found in the results of a survey of 16 vehiclemanufacturing plants showing a loss of $94,400 for 1918 due to bluing and molding of vehicle stock in transit.

PREVENTIVE METHODS

HISTORY OF PREVENTIVE METHODS

Attempts to solve the sap-stain problem in the United States date back to 1888, when lime in various forms was used on the boards and under the lumber piles. These efforts proved ineffective, and in some instances complaints were registered, because it was believed that the lime dulled the planer knives.

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Bryant, discussing the early history of sap-stain dipping practices in lumber, states: "On December 15, 1903, George C. Cowles, of Bay Mills, Mich., was granted the first patent on a process to prevent sap stain. (Letters Patent No. 746678.)" The chief feature of this patent was the immersion of the lumber in a 5 per cent solution of bicarbonate of soda (NaH CO3). This patent was declared invalid by the Grand Circuit Court for the Western District of Michigan, on July 23, 1908, on the basis that it did not embrace any new patentable ideas. (Lumber Anti-Stain Co. v. Geo. Nester, John Nester, et al.)

Since 1903, when the dipping of lumber in alkali solutions to prevent sap stain became common, considerable experimental work has been done by Government bureaus, and by others, in an attempt to find better methods of prevention. The first record of the use of chemical dips, for this purpose is to be found in the experimental work done in 1905-6 by Chapman in North Carolina, and by H. von Schrenk and others in Missouri and Wisconsin. From 1907 to 1909 considerable experimental work was done by the Forest Service and the results published by Weiss and Barnum in Forest Service Circular 192. In 1909-10 Hedgcock carried out a series of experiments, using various solutions on veneer stock. Teesdale in 1912, Knowlton in 1914, Kupfer in 1916, Pettigrew in 1917, and Howard in 1918 carried out various dipping experiments. Howard's studies on the sap stain and decay of vehicle stock were published in 1922 in United States Department of Agriculture Bulletin 1037.

A summary of the various tests made with sap-stain preventives from 1905 to 1922 is given in Table 3. The outstanding, promising chemicals of the entire group of experiments were found to be limited to a very few, such as mercuric chloride, sodium bicarbonate, sodium carbonate, sodium fluoride, and borax. Of these, the first had to be rejected except for special uses, on account of its poisonous and corrosive qualities. Of the remainder, the sodium carbonate-sodium bicarbonate mixture has been used extensively with varying and not entirely satisfactory results. After several years of practical application, even with all these experiments as guides, no entirely satisfactory method of preventing sap stain under all conditions has yet been developed. This coupled with the fact that blue-stain losses are being more keenly felt, has resulted in a decision to attack the problem anew.

as Bryant, R. C. Lumber: John Wiley & Sons (Inc.), New York. Pp. 220-21. 1922.

The various means employed in the prevention of sap stain vary greatly and range from end coatings to steam treatments.

END COATINGS

Of the various methods employed in preventing losses during log storage, the following are to be recommended: Coating the ends of

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FIGURE 25. Birch logs stored in the yard of a plant manufacturing wood derivatives. These logs are piled without foundations. The fruiting bodies of the yellow cap fungus, Pholiota adiposa, are observed emerging from the heart rotted areas

logs with various mixtures; spraying the entire log with chemicals; storing logs under water; decking and rapid seasoning; and barking followed by rapid seasoning. The best method is to avoid slow handling or long storage, if possible.

TABLE 3.-Summary of dipping experiments conducted by various investigators in the prevention of sap staining and molding of wood

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150 pounds aqueous solution needed to treat 1,000 board feet. Hand dipping, 2 men can dip 2,000 board feet per hour.

2 See Experiments in the Prevention of Staining and Molding in Lumber and Other Wood Products, by G. G. Hedgcock.

TABLE 3.-Summary of dipping experiments conducted by various investigators in the prevention of sap staining and molding of wood-Continued

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Third progress report, R. L. Pettigrew, June 18, 1917, Forest Products Laboratory. J. J. White Lumber Co., Columbia, Miss.

Many individual mills throughout the country, unable to avoid storage or slow handling, have tried an assortment of methods without, however, obtaining uniformly satisfactory results. As early as 1907 von Schrenk 39 tried coating the ends of red gum logs with a thin layer of coal-tar creosote and found this treatment fairly successful. Although preventing the stain and rot fungi from entering the ends of the logs, this treatment did not prevent the entrance of these fungi through the broken bark along the sides. The cost of this end coating was 8 cents per thousand board feet. An ideal end coating may have the following specifications: Cheap and does not discolor wood; easy to handle and apply; not easily removed by water; not harmful to the saw; effective in preventing stain, rot, end checks, and to some extent insect damage. With these specifications in mind, preliminary laboratory tests were conducted in 1924 and 1925 by the writer while at the Forest Products Laboratory. Some of these were tests carried out with pieces of wood sealed in glass jars; a few others were experiments in which fresh green branch and trunk sections of box elder (Acer negundo) were used.

von Schrenk, H., Sap Rot and Other Diseases of the Red Gum: U. S. Dept. of Agri. B. P. I. Bul. 114: 1-37; 1907.

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