Tuesday, September 28, 2010
When is a Veneer Hammer not a Hammer?
I have made a career out of working with veneer. I learned by experience. All the books I read at the start provided me with information which turned out to be wrong. These "how to do it" woodworking books told me to use the wrong glue, the wrong substrate, the wrong veneer tape, the wrong veneer saw...it is amazing that I even persisted long enough to get it right.
That is exactly the point I make to people who ask me about hammer veneering and working with a hot glue pot. Just do it (sorry about that Nike). Nothing beats experience and practice. Use scrap wood and scrap veneer and just work with the glue until you develop a system that works for you. Don't spend time reading books (or blogs, for that matter) and thinking others can tell you the best way.
In the first place, the business of cooking hot glue in a shop is almost a lost art. American woodworkers threw out the glue pots soon after the first World War, in favor of the new synthetic glues that modern science promised us were much better. Now, if you want to buy a wood glue, usually you go to the local hardware store and ask the salesman, which is best for your job. This salesman never used the glue, I suspect, but knows which brand he is promoting that week, and where the profit is for the store, so he hands you a product with confidence. Don't get me started about the strongest glue on earth...
In this post I will direct you to Keith Cruckshank's excellent site, Woodtreks.com for his videos; just click on the link on the right. He offered to visit me recently and produced several excellent videos on working with protein glue, hammer veneering and my workbench. We spent a lot of time shooting the video on cooking glue and understanding the properties of animal hide glue. We shot take after take during the process so he would have different camera angles and could edit it professionally. It came out fantastic.
When we finished, he said that it was time to shot the hammer veneer video. He was very concerned when I said "Get ready. It happens quick. You only have one chance, since it is something that only takes a minute." He was amazed when I picked up a piece of veneer, put the glue on the board and pressed it down with the veneer hammer. It was done before the minute expired. My complements to Keith for expanding that demonstration into a 10 minute video.
The tool traditionally used is called a veneer hammer. It is not a hammer, but looks like a hammer. In fact, it is held backwards, with the head pressed firmly on the surface of the veneer by one hand, and the handle pulled, pushed and moved from side to side by the other hand. It is not a hammer but a squeegee. It is used simply to press the glue, while it is liquid, quickly from the center of the veneer panel out to the edges. This motion must be completed before the glue gels. If the project is too large, an iron set on low heat is used to work the veneer ahead of the hammer to keep the glue liquid.
In the early workshops, if the project was large (like a piano top) several workers worked at the same time to hammer the veneer as quick as possible. This was a challenge in cold shops in winter. What talent!
The reason this method works is that the atmospheric pressure on the surface of the veneer exerts over 13 pounds per square inch of clamping, as long as there is no air under the veneer. As soon as the glue gels, it prevents air from entering under the veneer and the job is done. That is why the worker keeps pressing the veneer with the veneer hammer for several minutes until the glue reaches room temperature and gels. That's the entire "secret" of hammer veneering.
You won't believe it until you try it. Stop reading this blog and start cooking your glue. (Watch the video first!)