I recently ran into a problem when I attempted to lay some paper backed veneer with liquid hide glue using the hammering technique. The technique is simple, put a coat of hide glue on the substrate [that to which you are applying the veneer] and a coat of glue on the veneer on both sides to equalize moisture to prevent curling. The sheet of veneer is then placed on the substrate and a veneer hammer is used to pressure squeegee the veneer to the substrate by close adhesion caused by the thin blade of the veneer hammer and the gripping power of hide glue. And when hide glue dries of course it shrinks and holds the veneer tight.
I had to conduct a workshop to teach a half a dozen woodworkers how to hammer veneer. I was assured that they had the substrate material and some veneer to work with. The veneer was a sheet of hickory and white oak, both with resin paper backing. Rolled up for storage, the hickory had a real memory and proved difficult to handle. The white oak was better but after my first attempt it failed. Fortunately this was discovered before the class and we had time to pick up some un-backed alder veneer, un-backed veneer is getting harder to find. While alder is not the best wood and this stuff had knots, it worked out well and that is what I used in the workshop and all had success. Because of some extra time on the last day many built their own veneer hammers and plan on using them.
The upper veneer hammer is the one I made about 12 years ago, hickory handle, maple head and boxwood blade. The lower one is typical of the hammers made in the class, it has a maple handle, mahogany head and lignum vitae blade
I mentioned that some old examples had turned heads and one of the fellows in the class made this one with a mahogany handle, walnut head and lignum vitae blade.
I however was not about to let this paper backed veneer get the best of me. Upon examining the veneer I discovered that it was a resin coated paper, something new to me, but then most modern innovations are. The hammer veneering technique just didn’t work, while it went down, it soon curled up on the edges of the long grain of the veneer. So following tradition and heeding my own advice, I toothed the paper back of the veneer and scratched the hell out of the paper until it was completely toothed.
I sold my other steel glue comb so I had to make one for the class, it is about 2″ by 3″ , made of pure zinc sheet with the notches filed with a triangular file.
I used a notched glue comb [like a notched mortar trowel] to apply a uniform layer of glue on the substrate and spread glue on the rosin/paper and smoothed it with the flat edge of the comb to make sure it was wet. I also spread glue with a bit of water on the top of the veneer to prevent curling of the veneer from uneven moisture and to provide some lubrication for the hammer.
And after hammering down the paper backed veneer and allowing it to dry, it worked well. So if you are going to use rosin paper backed veneer, make sure to tooth or key the paper before hammering the veneer down.