Pro Woodworking Tips.com-Hide Glue

Hot Hide Glue

Hot Hide Glue, a love hate relationship...

Using hot hide glue, which is made from animal bones, hooves, and hides, is a practice which has been used for centuries. While some of the techniques, or more accurately, the support tools for working with the sticky substance have improved, it's still the age old process. Plus this stuff smells great! (not really)

The glue comes in flakes or granuals, and must be added to cold water, as per the directions on the container, in advance of using. The water dosen't disolve the flakes, it basically activates it for use. After about an hour and a half, you pour off the excess water, and pour it in the hot pot. The resulting mass is like globs of rubber or gel, so it doesn't exactly pour into the pot, it kind of drops in. This material must be heated to a temperature of about 140 degrees. Special glue pots are available, which are designed just for this purpose. ( photo 1) They have automatic temperature controls built in, which is handy. As the glue sits in the pot, it developes kind of a crust on top, which can be stirred back in.

A notched trowel or stiff brush is is ideal to spread this thick sticky glue. As soon as the glue has been applied to the substrate, the veneer is laid in place, and coated on the surface with more glue. The surface glue is used as a lubricant for the veneer hammer, (photo 2), which is used more as a squeegee, to squeeze the excess glue from under the veneer. The hammer is usually worked from the center, out towards the edges, forcing the veneer down to the substrate. The mass of the hammer cools the glue as it's being worked, and the resulting bond is impressive. One thing to consider while working with hide glue is the fact that there is substaintial shrinkage, which could cause problems with the veneer. Any flaws in the substrate will be obvious once the glue shrinks. Any loose spots found later can be ironed down, and will stick just fine.

This process is a lot of work, and for this reason, is rarely used in commercial shops. Clean up must be done with warm water. Cold water will just harden the glue.

You may be wondering why anybody would use this glue, but it has it's advantages. For one, it's reversable. You can use heat or steam to undo the glue joint. Antiques being repaired are generally required to be done with hide glue in keeping with the original construction. For veneering curved parts, it's often easier than using a form and a vacuum bag. There are a number of instances where it's the best thing since sliced bread. But be prepared for a workout, as it's a physical process. The glue that was used as a lubricant must be scraped off the surface, prior to finishing.

A good source for buying hide glue and other veneering tools is: www.toolsforworkingwood.com. These are serious people, regarding the tools they sell.