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Hardwood Record — Veneer & Panel Section 



January 25, 1917 



Laying Fine Veneers 



Proper Glue Consistency Has a Great Deal to Do with Good Work 



SJ LAYING fine, thin veneers, such as finely- 

 figured or crotcK/tnahogany, Circassian walnut, 

 or butt American "walnut, is it necessary to wash 

 off the glue that has been drawn through by the 

 hot cauls, before a clear, distinct finish can be obtained? 

 That is, prevent glue which has penetrated to the out- 

 side, from being noticeable after the goods are finished? 

 We find thai unless the washing is done with great care 

 the result is a tendency on the part of the veneer to 

 crack and come loose. The above is one of the problems 

 recently brought to the writer's attention. 



In my opinion it is not necessary to wash off the glue 

 in order to obtain a clear finish, provided a water stain 

 is used on mahogany stripe and crotch veneers. Where 

 an oil stain is used it is different. Those parts which 

 allow glue to come through in such quantities are mostly 

 end wood on the face, and the glue which is impervious 

 to oil stain has penetrated every pore and fibre of the 

 wood, consequently the oil stain will not "take," and 

 those places when finished have, in comparison with the 

 other parts, a somewhat faded appearance. TTiis faded 

 effect is more pronounced where a medium dark shade 

 is desired. But w^here a water stain is used it will 

 penetrate and neutralize the glue and destroy its effect 

 upon the finish. One thing that is sometimes done is 

 to make the stain for crotch extra dark and wipe it off. 

 Of course this must be done quickly or the cloth used in 

 wiping will stick to the glue and smear it. 



But all this is a cure. Would it not be better to get 

 at the cause of the trouble and prevent it as far as pos- 

 sible? I do not think that it is possible to entirely pre- 

 vent glue coming through some kinds of crotch mahogany 

 and Circassian walnut, but I do believe that much of 

 this trouble may be avoided by a judicious selection of 

 core-stock to match the texture of the veneer with which 

 it is to be used, and the proper preparation of the glue. 

 The face of most crotch and some Circassian veneer is 

 end wood and will absorb glue rapidly; to present this a 

 heavier glue should be used. Now, if we are going to use 

 a veneer that requires a thick glue, a core-stock should 

 not be used that requires a thin glue, unless it is well 

 toothed to enable the glue to take a firm hold of it, and 

 then a glue should be used suitable for the veneer. 

 Right here, I think, is to be found not only the cause of 

 the glue cojiiing through, but the cause of much of the 

 coming loose complained of. If a gfue is made to suit 

 the core-stock without regard to the requirements of the 

 veneer, the absorbing parts of the veneer will take it all 

 up in the pores and not leave enough beneath to hold 

 it firmly to the core-stock. Then, when we attempt to 

 wash it off (which is not washing "off" but "out," as I 

 presume the face has been scraped and there is no glue 



left except what is in the pores) the water penetrates the 

 pores to what little glue is left beneath and softens it. 

 Although this washing may have the effect of raising the 

 veneer, I am of the opinion that where glue has been 

 used thin enough to enable it to force itself through in 

 large quantities, the veneer would come loose in time 

 even under the most careful treatment. 



Neither do I think that the washing is the cause of 

 the checking complained of. It is a common thing to 

 see fine striped veneer with checks one-half-inch long 

 and one-half to one-inch apart running across the dark 

 stripe, while the rest of the veneer is intact. Let us 

 examine this for a moment. The face of this dark stripe 

 is end wood and very brittle and the contraction of the 

 core-stock would have considerable effect upon it. Much 

 cross-banding that is used is far from being dry, and if it 

 shrinks beneath the veneer, the latter breaks at these 

 hard, brittle spots while the rest of the veneer is tough 

 to resist it. It is the same with crotch and black-butt 

 walnut and some kinds of Circassian. The writer has 

 seen cases where, three months after these veneers were 

 finished, and where no water at any time had been used 

 for any purpose, they have checked in scores of places 

 and the edge of the veneer at the check curled up from 

 the core-stock. 



Another thing to which too much attention cannot be 

 given in laying these fine, delicate veneers, is to see that 

 the cross-banding is laid right side up. This important 

 detail is very often overlooked in the belief that the face 

 veneer will cover and hide all defects. Much of the 

 heavy rotary-cut cross-banding is very scaly on the wrong 

 side, and if it is laid with this side up many of the scales 

 are strong enough to raise and break the face veneer in 

 these tender places. B. M. 



It is not an unusual thing, especially around planing mills using 

 veneer, to find a warm room or compartment used for drying out 

 veneer and core stock. They are also being found more and more 

 in connection with furniture factories, and they help in a way, 

 but not always in the right way. 



Any man with a room of this kind, or who contemplates set- 

 ting up and using a warm room, either for stock previous to gluing 

 or for setting after gluing, should remember that ventilation is 

 essential to drying, even in warm air. The warm air will take 

 up only a limited amount of moisture from stock piled in it, and 

 to do the drying out as it should be done the warm air in the 

 room must be carried off and fresh air let in. The air is a vehicle 

 for taking up and carrying off the moisture, and if ventilation 

 is not provided so that fresh air may be coming in all the time, 

 the air in the warm room becomes saturated and remains there, 

 with the result that the stock becomes warm, but not dry. 



So have the warm room, but ventilate it to get good results, 

 for merely heating stock is not drying it, and proper drying calls 

 for air to pass through the stock and out. 



