glue,veneer, substrate.....

M

mikemcgrail

Well-known member
I am always wondering how so many 19th and late 18th century pieces seem to have survived "well" even though they are almost always veneered on only one side. I had always thought it was the lumber used for the substrate. It seems to me the backer was often a white pine or deal pine(on english pieces), and the veneer is almost always what I would call san domingan mahogany. I did try experimenting about 15 years ago with some crotch walnut and some really fine quartered white pine(the kind that seems born to stay straight). Still, I didn't really think it stayed true. I did use the yellow titebond glue. Does anyone know about the relative difference in the amount of moisture in the glue(between the hide and synthetic) that is absorbed by the wood?
I just wonder about these things. I know I can veneer the back side and probably keep it straight. I had always thought it was the lumber. 25 years ago, a friend gave me a piece of old pine from a building and assured me it would always stay straight. I still use it for a straight edge. I have thought since then it was the wood that let the old guys veneer "one sided".  Anybody ever try to lay veneer with a glue with no water base, like epoxy?
 
I can't really comment on the glue as I've not done any experiments, but I would guess hide glue would give up as much, if not more moisture than PVA since water is the solvent/carrier, and hide glue cures by evaporation of the water, not a chemical reaction like PVA.

I wonder, however, if the hide glue doesn't "breathe" more since it's protein based and not plastic based like PVA. Since hide is transparent to finishes, I would expect that air could get through it as well. Maybe not so for the PVA? Perhaps the moisture barrier created by PVA slows moisture equilibration when the humidity changes vs. faster, more even equilibration in the hide glue veneered piece since it would breathe more? I'm just guessing here.

Some other thoughts/guesses: Air dried wood (veneer & substrate) 250 years ago vs. kiln dried today? Thicker hand sawn veneers then vs. today's paper thin ones? Slower growth, more stable wood (veneer & substrate) then vs. faster growth, less stable wood today? Again, just some theories. I have no research to prove/dis-prove any of this.
 
Mike,
        My experience with veneers on one side seems to always cause cupping at the outer edges toward the veneered side. I just assumed it was from the moisture entering the back side of the board or the veneer pulling the substrate as it dries. The wider the substrate the worse it it. I wonder if sealing the back side first would help stop this? I have taken some veneered boards and set them outside in the sun with the veneered side down and it will staighten up some, enough to get it in the frame. The thinner the substrate the worse it is. Big problem with moisture here in Louisiana.
                                                                          Michael Armand
 
I am not really trying to use this technique as much as I am trying to understand how it was used so widely in the past. My suspicion is now that the hide glue was a major factor, as Bob suggests. I wonder if anyone here has tried hide glue over some stable looking white pine with 1/10 or 1/12 thick sawn face.
I would just like to understand how itcould have been done so widely in the past. Even if the home it was in wasn't well heated, I would still think there would have been great swings in relative humidity.
 
Mike- If you make up your draw and glue it up before you veneer it, the sides tend to keep it flat-Al
 
  Remembering that I am primarily a furniture repairman "restorer, conservator", and see mostly the pieces that have problems, here's a list of thoughts on veneering.
1. There is no rhyme or reason for what was used for substrate. In my shop right now I have at least 100 pieces for repair. Most of the veneer is on pine or poplar, and most of it is plain sawn and a lot of it is not flat. I have even seen rosewood on knotty pine.
2. I don't believe historic wood is any more stable than current lumber.
3. Remember that a great deal of the furniture we see in museums and books has been extensively restored often several times. Unrestored historic pieces in the original finish are very very rare if they exist at all.
4. Al is right many pieces were veneered after construction.
5. The actual pieces of veneer on old pieces tends to be smaller and applied in stages, large sheets of veneer on large flat surfaces tend to be rare.
6. In the process of hammer veneering the surfaces are sized this may help limit moisture penetration, also in hammering all the excess glue ( moisture) is squeegeed out.
7. Old veneer can be very thick. I have seen drawer fronts where the veneer varies in thickness from more than 1/8" to almost nothing at the same time the substrate also varied. It appeared that the front had been planed after it was veneered.
 
Mike:  Lots of great thinking going on here, I often wonder if we modern makers aren't much more obsessed with perfect or flatness to the "Nth" degree than makers from the 17 and 1800's.  Not that they were not amazing crafts people but they did not have CNC level perfection in any area of their lives and so were far more concerned about the end product being functional and looking good.  I suspect as well that the survival rate of veneered surfaces was better in some parts of the country than others due to the variation in humidity.  In 1959 my grandparents moved from Stamford Connecticut to Denver Colorado with a house full of great pieces they'd collected over the years.  Within a year every single piece was having delamination issues severe cracking and warping.  I inherited a Federal Style tall clock that had warped terribly and in many places had literally shed it's veneer like dead skin.  This might be an extreme example but I suspect our modern heating, cooling systems and our plastic based adhesives as well as our far less mature wood all contribute to the problem.
C J Struthers
 
Perhaps "survival of the fittest" and luck also play a role. 
Once I asked why people raved about antiques with wide boards but weren't willing to build new with wide stock.  One respondent suggested it's possible that perhaps 99 out of every wide board piece built in earlier times failed, so that surviving examples were the exception due to unique grain pattern, wood stability, et cetera.
Atypical materials, atypical construction practices, and atypical environmental conditions perhaps help the occasional piece remain in good condition that otherwise should not?
 
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