US1810659A - Process of treating wood - Google Patents

Description

June 16, 1931. w. KRlTcHEvsKY ET AL 1,810,659

PROCESS 0F TREATING WOOD Filed Feb. 14. 1929 atented June i6, 193i` i 'WULF KRTCHEVSKY ANDy CARL J'. BECKERT, OF CHICAGO,

v orsics ILLINOIS PROCESS F TREATING WOOD vAmalication led February `14, 1929. Serial No. 339,910.

ln the productionof lumber and veneer from black walnut logs, a substantial loss is occasioned by the necessity for utilizing only .the heart wood which is of the desired color, and discarding the sap wood which constitutes twenty'to` thirty percentof the whole log.

- The quality of the sap wood, except for the color, is equal or superiorY to that of the l0 heart wood, and this invention relates to a methodof eiecting the coloring of this valuable portion of the walnut log.

We are aware that various processes of coloring the sap wood have been suggested,

l5 but in none of the processes has the problem been solved, -from a practical standpoint,

either chemically or physically. The addition of color is expensive, uncertain and unsatisfactory.

wWe have discovered that the coloring matter in black walnut ispresent in the natural sap wood in chemical combination as a glucoside or ester, with some form of sugar, or

with cellulose or lignin. This coloring matter, in the natural growth of the wood, be-

comes oxidized or hydrolized very slowly and gradually by changes of temperature and other: natural causes, the process extending over a long periodl of years. Naturally,

' 30 therefore, the coloring proceeds from the center outward.

We have4 discovered that this chemical reaction may be hastened by the application of heat and pressure and the process completed in a few hours.

That the theory above expounded is correct is borne out bythe fact that sapwood and heartwood indiscriminately may be 40 treated by our process without change in the color of the heartwood, the sap-wood being colored to exactly the shade of the heartwood and indistinguishable therefrom, This would seem to prove that a certain definite quantity of the coloring matter is present in to assist in the material from charring or breaking down unthe natural wood, which, when developed produces the desired color.

The apparatus necessary to the carrying out of the process is simple, and consists merely of a pressure type container of the required size with pipe connections for the Y admittance of steam. A pressure kettle such as contemplated is illustrated in the accompanying drawing in which the figure is a perspective View thereof.

The autoclave or pressure-container may be of any desired size having the cover 10 with' clamping bolts 11 Jfor securing the cover in place. A steam admission pipe'is indicated at 12 and a water admission pipe at 13.

A steam pressure gauge is indicated at 14 and a thermostatic regulating unit at 15. Inasmuch as the treatment is by'steam under pressure and as the temperature is a function of the pressure, a pressure regulatormay be substituted for the thermostatic regulator if so desired.

Instead of supplying steam. directly to the tank, heat may be applied to the exterior of the tank, which will vaporize the water therein and develop suitable pressure.

In carrying out the process, a quantity. of water equal to approximately ten percent by weight of' he wood to .be treated is admitted into the container. It is essential that water in at least the uantity indicated be present ydrolysis and to protect the der the temperature.- A much larger quantity of water may be used if desired, butl the amount indicated has been found to be satisfactory.

After the waterhas been supplied and the container is tightly. closed, steam is admitted at atemperature of from to 160 degrees centigrade with corresponding pressures. In' l ractice, we have found that a temperature of from to 140 degrees centigrade with a pressure of from 35 to 40'pounds is most satisfactory. With a maintained temperature ther, that the time varies in inverse proportion to said temperature and pressure. The proportion however is not direct, it being neither arithmetical nor geometrical, but varies according-to a formula that we have not yet determined.

It has also been found desirable in order to facilitate the treating process and to improve the wood fiber, to cook orsoak the material in hot water with some penetrating agent in solution before placing in the container. This, however, is an optional pretreatment that does not affect the operation of the described process except to lessen the time required for its completion.

From the above description it will be apparent that the material either in the form of logs, lumber, or veneer may be treated indiscriminately as to heartwood and sapwood, no changes in the color of the heartwood resulting therefrom. This is a very great advantage as it eliminates the necessity for separating the two classes of wood before treatment.

.While we have dcscrib'ed this process as peculiarly adaptable to the coloring of black walnut it will be understood that the process is equally applicable to the treatment of other kinds and descriptions of wood, particularly mahogany and gums in which we have found the same chemical conditions as described in connection with black walnut.

We have attempted to outline the process within the limits that have been found to be practical, and feasible.

We realize ,that variations and modifications may be made in the process following its use, by those skilled in the art, and we do not wish to be limited except as indicated in the appended claims.

We claim:

1. The process of treating wood which consists in placing the Wood in a container, supplyingwater to the container, and subjecting the material in the container to steam presy sure above atmospheric.

2. A process for treating sap Walnut which consists in placing the same in a closedvessel in the presence of an amount of water equal to from 10 to 60 percent of the weight of the wood and subjecting the contents to ahsteam pressure of between and 50 pounds.

' 3. The method of treating` wood which consists in pre-soaking the wood, and then subjecting the wood to steam pressure above atmospheric.

4. A process for treatingr sap Walnut which consists in subjecting the material to presoaking, then placing the same in a closed vessel in the presence of an amount of water equal to from 10 to 60 percent of the weight of the wood and subjecting the contents to a temperature of 120 to 160 degrees C., and steam pressure above atmospheric.

ln testimony whereof we have affixed our signatures.

W. KRITCHEVSKY. CARL J. BECKERT.

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