US2532193A - Process for impregnating wood with sodium thiosulfate - Google Patents

Description

, R. G. RAMSEY 2,532,193 PROCESS FOR IMPREGNATING woon WITH SODIUM THIOSULFATE Nov. 28, 1950 4 Sheets-Sheet 1 Filed July 21, 1947 Rffiamse M N \XW 4 Sheets-Sheet 2 llllllllu'llllllll r l l R. G. RAMSEY PROCESS FOR IMPREGNATING WOOD WITH SODIUM THIOSULF'ATE Nov. 28, 1950 Filed July 21, 1947 Nov. 28, 1950 2,532,193

R. G. RAMSEY PROCESS FOR IMPREGNATING WOOD WITH SODIUM THIOSULFATE Filed July 21, 1947 4 Sheets-Sheet 3 Nov. 28, 1950 R. G. RAMSEY PROCESS FOR IMPREGNATING woon WITH SODIUM THIosuLFATE 4 Sheets-Sheet 4 Filed July 21, 1947 3% R.Gf?am5eg MM 46 at the opposite end thereof. A substantially ring shaped member 41 is secured to the forward end of the frame 44 and provides a handle by means of which the carriage 43 may be moved from supply of wood toward the pressure tank l and away after treatment to place where materialis used and thereby keeping the wood hot by the carriage, which is an essential part of the process. The carriage 43 has secured to the forward end portion of the bottom wall 29 thereof an angle member 48 which is formed with a horizontally disposed forwardly projecting flange 49. The angle member 43 and the flange 49 provide a reinforcing means for the forward end of the bottom wall 29. The carriage 43 has mounted in the tracks or rails 42, stop members 50 which limit the movement of the carriage 28 onto the carriage 43 when the carriage 28 is removed from the pressure tank ill. The rails or tracks 38 also have stop members 5| adjacent the inner ends thereof which are engaged by the innermost pair of Wheels 31- so as to limit the inward movement of the carriage 28 into the pressure tank to.

In the process of treating the wood, the wood is placed in the wood treating carriage 28. The wood, if in strips is laid on the fiat bottom 29 in layers which may be uneven, so as to provide spaces between the wood or wooden strips for circulation of heat and for the flowing of the sodium thiosulphate together with the moisture of the wood which flows from the wood in the course of the treatment. After a layer of wood has been placed in the treating carriage 28, sodium thiosulphate is distributed thereo-ver, and then additional layers of wood are placed on top of the sodium thiosulphate. The procedure is continued until substantially the entire area of the treating carriage is filled with layers of wood and alternate layers of sodium thiosulphate with a layer of sodium thiosulphate on the top layer of wood. Some of the layers of wood will be exposed as to their lengthwise edgesthrough the space 36.

Additional sodium thiosulphate is concentrated near the ends of the wooden strips on each layer through the space 36 and also on top of the uppermost layer of the wood. This has the advantage of giving the ends of the wood a stronger sodium thiosulphate treatment where it i generally most desirable as the wood ordinarily is most apt to split near or at the ends. The carriage 43 is moved toward the tank as sothat the tracks 42 will engage the coupling members or guides 4! in order that the tracks will be held in alignment with the tracks 38. The wood treating carriage which is now filled with wood and which has the sodium thiosulphate on the interior thereof is moved inwardly of the pressure tank ID. The end wall I3 is then closed and locked and steam heat is admitted through pipe 26. The steam is preferably dry steam, and under a pressure of from 60 to 150 pounds per sq. in. but less pressure can be used by giving the wood a longer period of treatment. During this time the temperature ranges from 292 degrees Fahrenheit to approximately 3'70 degrees Fahrenheit. The wood is subjected to the steam pressure for a period 4 of from 15 to 20 minutes, depending on the pressure of the steam. The heat will cause the sodium thiosulphate to dissolve and a the solution of the crystals is under pressure this solution will be forced into the pores and fibers of the Wood so as to impregnate the wood.

Following the pressure treatment of the wood, the treating carriage 28 is removed from the pressure tank. The wood is kept hot in the treating carriage 28 by insulating or covering means of any suitable character to retain the heat in the wood until the wood is bent and used. The process hereinbefore described provides a means whereby the wood will more readil bend with- 'out checking or cracking and will more readil retain its bent form after it has cooled to normal room temperature.

By using sodium thiosulphate in place of urea in the treatment of Wood a smaller amount of material, sodium thiosulphate, is used and the same work is done in less time. Only about two thirds as much sodium thiosulphate is needed as urea, and the time required is from 15 to- 20 minutes for sodium thiosulphate as compared to 40 to '75 minutes for urea. The length of time required for this treatment cannot be varied by varying the amount of material with which the wood is covered.

The exact configuration illustrated is regarded as the optimum, but some of the desirable results inherent in this disclosure may be obtained by various slight modifications including some departure from the exact configuration shown, and it is therefore, requested that the scope of the invention should be regarded as limited only by the terms of the claim.

What I claim is:

A method of treating wood to prevent splitting and cracking which comprises placing a layer of wood in a receptacle, covering said layer of wood with crystalline sodium thiosulphate, concentrating additional sodium thiosulphate adjacent the ends of the layer, adding a second layer of wood and repeating the process and subjecting the stacked layers of wood and sodium thiosulphate to dry steam between 290 F. and 375 F. at a pressure between and lbs. per sq'. in. for a period of time between 15 and 20 minutes.

RAYMOND G. RAMSEY.

REFERENCES CITED The following references are of record in the file of this patent:

Great Britain June 7 1934

Images