Hide glue

Until now I have used "standard" Pvac glue for assembling all my woodwork projects. Overhere in The Netherlands know as the white wood glue. You can buy it everywhere, and it is rather cheap and easy to use. In the past, say until WW2, a natural glue made from the bones and skins of animals was the standard. Hide glue, or bone glue as it is know overhere. The bones and skins are cooked for a very long time, filtered and dried. You can still buy it, usually in the shape of small pearls. It's also pretty cheap, but not so easilly available. To use it you must dissolve it again in water and heat it around 60 degrees Celsius.

When I bought an old carpenters chest, I found a double cooking pot for glue inside this chest. Water is heated in the outer pot and the glue gets hot "au bain marie" in the inner pot. You put the pot on a stove and let it simmer slowly, all the time watching the temperature, because really cooking the glue destroys the adhesive properties. 60 to 65 degrees is ideal and higher not recommended.

Hide glue has its own pace. It's not like you  grab the bottle and squeeze some glue on your joint. First the glue pearls must be dissolved, which takes about two hours. Then you heat the glue pot to the required temperature. You stir a lot and watch the viscosity. It should be sirup like, not too thick, but also not watery. In the mean time you heat up the workshop and ideally also the wooden project, because you need warmth for the next step. Until now everything moves very tranquile and feels relaxed. But actually gluing your joints needs tremendous haste. Within a minute or so the glue cools and starts to gel and the joint shouldn't move anymore. For simple joints this is ideal. You don't need clamps, you just hold the parts together until you feel the glue grabbing. Complex joints are a bit stressy.

As soon as the initial gelling of the glue happened, it's time to relax again. The next phase is evaporation of all the water. This takes a much longer time. After a night the glue is allready very strong and the joints can be fully stressed. The strength will increase further, depending om the humidity of the environment.

So, why did I want to use hideglue? Good question. Probably because I just want to use that gluepot. And because it is new skill to learn. Some pictures. First the glue pot. I have added an extra pot, in this case a used glass  jar. This is a bit smaller thus better suited to my projects and it is easier to clean. A meat cooking thermometer to watch the temperature and a brush for stirring and applying the glue.

I did a lot tests this weekend to get familiar with the process, and to actually gain confidence in this glue! I didn't need to worry. It is slow, but when it dries it glues like crazy, stronger then pvac I think. So, on to my project. I did mostly one joint at a time, then letting it rest for a while to get a bit of initial strenght in that joint.  I glued the legs to the short rails and I glued the long rails to the very short rails in the middle. The latter with through mortises and wedged tenons. That was allready stressfull enough! I will assemble these parts together later this week when the glue is completely dry.

Clean up is easy with this glue. After a while the squeeze out is rubbery and can be pulled of the wood. A hot damp towel removes the rest, without a trace left. That is at least one big advantage of hide glue. The other big advantage? It's fun!