Monday, October 4, 2010

Got a Toothing Plane?

I encourage every woodworker I meet to use animal protein glue. In 40 years of preaching about the glue and its advantages, I have not yet met a person who could convince me that he had a better glue for woodworking. Believe me, I have had some lengthy discussions about the merits of glue.

For example, the advertisement that one glue is "the strongest glue on planet Earth" always seems to come up. I won't address the facts that hot glue and liquid glue tested stronger than that glue in Fine Woodworking's objective testing (Issue #192, July/August 2007). The real question is: do you want a glue that is actually going to cause the wood to break before the glue fails?

There is a study online from the Wooden Artifacts Group of the American Institute for Conservation of Historic Objects, published in 1990 which discusses this question, and compares liquid to hide glue for furniture conservation. The 16 page research paper concludes that liquid hide glue is actually preferred over hot glue in many situations.

However, there is still a reason to keep the old hot glue pot cooking. In the shop here, we have had a glue pot cooking every day for the past 40 years, and I think I have a good understanding of its working properties. Although I use Old Brown Glue (my own liquid formula) for about 80% of the repairs and construction, there is still a necessity for keeping the hide glue hot and ready. I use it for hammer veneering, rubbed glue joints, and, of course, those quick repairs that need a fast acting glue.

The real problem is finding a glue pot. I am on ebay every day looking for used antique glue pots for purchase. Unfortunately, there are hundreds of my students who are also looking and bidding against me. I used to have antique tool dealers in England collect them and send them to me, but the postage and breakage (not to mention the weak dollar) put an end to that.

There are also tool dealers online who sell glue pots. But if you just google "glue pot' you end up with a variety of hits, most of which are not related to woodworking. Fine, if you want hair extensions, but not so efficient if you just want an old rusty pot.

That is why I recommend that you search "toothing plane" in quotes to find a glue pot. Strange idea? In fact, a tool dealer who knows what a toothing plane is most likely also has a glue pot sitting in the back of the store. Just ask him.

What is a toothing plane, you may well ask? As I have a rather large collection of wood tools, I have always had a toothing plane. The very first plane I made was a toothing plane, in 1975, when I really began working veneers with hide glue. I could not find one for sale, so I made one to fit an old toothed iron I purchased.

The toothing plane is one of the most forgotten wood tools in history. It was created soon after the "ebenistes" in France started working with veneers, during the late 17th century. The "teeth" were chiseled into the plane iron, much like the hand made rasps were made. There were fine teeth for cleaning up the saw marks on the veneer, and medium and coarse teeth for surfacing the hand hewn surfaces of the oak carcase.

The blade is set at a steep (scraping) angle, with the teeth forward and the bevel on the back. The usual shape of the body is similar to a smoothing plane. The iron is sharpened only on the bevel side, and if you even touch it to a grinding stone it will burn the teeth. It must be hand sharpened on a stone, working only on the bevel to sharpen the teeth.

The pattern of tooth marks on the surface of the wood indicates the "truth" of the work. That means the ground work is evenly flat and ready to receive the veneer. It also removes any oxidation or dirt/grease which might be present. Most importantly, it increases the glue surface area, and prevents glue starvation which might occur when using non porous woods.

Therefore the tool kit for traditional veneering is a veneer hammer, glue pot, veneer saw (I use the French style saw shown in the picture), and a good toothing plane.

Ready? Set. Go!

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