

The Drying of Glued-Up Stock |g| 



In doing veneered T\ork the trade has learned among other things 

 during the past few years that the way to obtain the best satisfac- 

 tion and secure the highest order of work and finish is to take 

 time enough to thoroughly dry out the work after the veneer has 

 been applied. "While it matters not that the veneer and the core 

 stock when used has been thoroughly kiln-dried in preparation for 

 the veneering, except that it is essential to secure good work, the 

 fact remains that the moisture incident lo gluing which is taken up 

 by the wood should be dried out before the veneered work is put 

 up and finished. This really applies to both face veneering on solid 

 bodies, veneering on heavy cores, and the making up of panels. It 

 is not considered so essential where heavy cores are used because 

 the core body takes up and distributes the moisture through itself 

 so that it is not so much in evidence. Yet the fact remains that 

 proper drying should follow veneering even on heavy bodies and 

 in the makiug of two, turee and five-ply built-up panels it is one 

 of the essentials of the work. 



One reason all veneered work should be dried after gluing up is 

 that if it is taken direct to the sander from the presses the warmth 

 of sanding, with the moisture still remaining in the wood and in 

 the glue, is likely to cause the glue joint to loosen in spots and 

 cause blisters. It is found at times, too, that enough moisture re- 

 mains in the face veneer to make it sand poorly. 



In built-up panels drying after gluing up, vihile recognized as 

 one of the essential steps to proper manufacture, is often a source 

 of trouble because the man buying the panels wants quick shipment. 

 Even where a man is making his own panels he is likely to wait 

 until they are needed before making them up, and then there is 

 more or less of a fight over the question of allowing time for proper 

 drying after gluiug. 



Naturally all this has led to study and effort looking to ways 

 and means for the rapid and proper drying of glued-up stock. 

 Where there is plenty of time and where the panels can be made 

 up ahead of needs, the usual practice is to pUe them carefully on 

 cross strips in a warehouse and let them stand, say for two or three 

 weeks, before trimming and packing for shipment. 



In drying panels one may to some extent follow the same prin- 

 ciples that are resorted to in drying lumber but the extent is lim- 

 ited because high temperature is not permissible. For example, 

 it would not be practical for one to put glued-up panels in a hot 

 plate redrier, nor would it be practical to put them through one 

 of those patent endless belt or roller driers because the excessive 

 heat would do violence to the glue joint. What is needed for drying 

 the glucd-up stock is something to retain it flat and straight and 

 permit free circulation of air with cuough temperature in it to carry 

 off moisture rapidly but not hot enough to damage the glue joint. 



Special dry kilns may be arranged with trucks and piling strips 

 or racks and the temperature carefully regulated and held down to 

 whatever point it is determined will be safe, and in this way the 

 glued-up stock put through a kiln pretty much as one would put 

 the veneer through a kiln prior to gluiug-up. It could not go 

 through the same kiln, however, at least not with the same order 

 of treatment. The proper drying of glued-up stock in this way 

 would call for the building of a special kiln for this purpose, one 

 with plenty of air circulation and the temperature limited to a 

 point where it would not do violence to the glue joint. 



Perhaps the simplest and most economical idea along the line 

 of hastening the drying of glued-up stock is to provide the ware- 

 house with a hot blast apparatus for winter use. With something 

 of this kind arranged pretty much gs' one would arrange to keep a 

 house comfortably warm to work in, there can be put into the air 

 enough temperature to make it hungry for moisture so that it will 

 dry out the glued-up stock in a fairly short time. Some ventilation 

 must be provided but often if the overhead space is high the air 

 will find enough escape and the drying in the warehouse in the 

 winter would really just take on the form of heating the ware- 



house to a comfortable working temperature or a litlle abovf. It 

 has not been positively determined just what tempcraturo ordinary 

 glned-up stuff will stand, but it is perhaps safe to say that it will 

 stand anywhere from 70 to 90 and possibly 100 degrees, and during 

 cold weather with this much temperature in air blown into the build- 

 ing there will in most buildings be enough escape to provide the 

 necessary ventilation. 



In the summer the same apparatus may bo used with the heat 

 omitted or just a small amount of heat used. In warm weather 

 practically all that is needed to properly dry glued-up stock is air 

 circulation. If it is properly piled on strips in a warehouse, the 

 forcing of an air draft through it will carry off the moisture and 

 dry it out in a much shorter time than if it is packed in an en- 

 closed warehouse without any enforced circulation of air. 



The circulation of air should be studied and made systematic 

 so that it will circulate through the piles of built-up stock and 

 not merely about and around it. Different plans and details may 

 suggest themselves for this purpose. Usually where the air is heated 

 it should come in through ducl^ underneath, and it is a good plan 

 to have a series of ducts coming tlirough underneath the rows of 

 piled panels and other veneered work. No matter what details are 

 applied the air must circulate through the piles of veneer and not 

 merely around them. With plenty of air circulation, drying can be 

 hastened either with or without temperature — unless, of course, it 

 is damp drizzly wcatlier and the air itself is heavily charged with 

 moisture when it is blown in. 



The moisture conditions of the air itself should always be taken 

 into consideration. Air taken from the outside may vary consider- 

 ably in moisture content from day to day and the right idea of eya- 

 tematic drying should take consideration of this, and the tempera- 

 ture be regulated accordingly. If it is a damp day and the air is 

 already charged with moisture there should be more heat in the 

 coils through which it passes than during the dry bright day to 

 get the same efficiency in drying. 



Fortunately for this work some new schemes are now being de- 

 veloped for regulating the moisture content of the air used in 

 heating buildings. The blower people are making a study of beat- 

 ing and ventilating and have not only devised plans for washing 

 air to purify it, but they have actually developed ideas along this 

 line to the point where it is practical to regulate humidity as well 

 as temperature, and they can add to or take from the moisture con- 

 tent of the air as it enters the building. When air has too much 

 moisture in it they can reduce this moisture content, and where 

 there is not enough it is added to. This is a i)art of scientific 

 schemes for heating and ventilating factory and oflice buildings, and 

 it is a thing being resorted to by certain lines of business which 

 require air in certain specific condition as to humidity all the time. 

 It is what is called "air conditioning" and since it is practical in 

 other linos it should be comparatively easy to apply things of this 

 kind to the storage warehouse for built-up veneer so that it may be 

 dried out scientifically in the shortest period of time with every as- 

 surance of getting the best possible results. 



Some day entirely new lines of veneer work may be developed. 

 Every once in a while some one makes a strong appeal for us to 

 take up the Russian method, which consists in gluingup the veneer 

 green and drying it out afterwards, so that one drying docs it all. 

 Sometimes we hear of experiments with glue that is used with heat 

 as well as pressure, the heat setting the glue substance and drying 

 the veneer in a short time, and various other new things of this kind 

 may be developed. Meantime, the biggest possibilities seem to be 

 along the line of making a study of air circulating apparatus that 

 will enable the panel manufacturer and the furniture man to pro- 

 vide at all time the air conditions and the temperature necessary 

 to facilitate the drying of veneered stock in a way that will give 

 the most satisfactory results and reduce the time required to a 

 minimum. 



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