For a long time my dreams of some very gluey projects have been hampered by the cost of waterproof casein glue such as "Cascamite" From time to time I've searched the web in the hope of finding a recipe for home made glue of this type. At last I've found one. In case anyone else finds it interesting, here it is:
in it by the sink for three or four days?
I can't tell because the cereal bowls left by the sink four days ago are covered by the dinner plates left there 2 days ago.
commercially - or rather milk paint, which is very similar. To make anything more than a panful, or to have any repeatable product quality, it needed a spray drier.
Mary will of course be boiling up stag's horns or making viking cheese glue instead.
So, it can't be kept without spray drying, which I suppose may not be a viable d-i-y process. But for immediate use do you think it would provide a waterproof glue of a similar quality to Cascamite?
No, nothing like that dependable quality.
It'll work (although for home-made glue, IMHE rabbit-skin is easier). As a demonstration for kids it's excellent, as a piece of woodworking recreation it also has its place - Italian renaissance furniture, AFAIR. But I wouldn't trust it for boatbuilding !
The problem is with acid production owing to decomposition in service. As the Germans found in WW2, this is a big problem.
The German "Moskito" aircraft was a copy of the British Mosquito, likewise made by a bonded plywood process. When built with the original "Tegofilm" adhesive, a hot-melt sheet (aliphatic PVA ?) it was a fine aircraft. But the REAF bombed the Tegofilm factory and so an ersatz glue had to be found. Now AIUI, this was a casein glue. It was soon found that the Moskito developed a tendency to break up in flight, caused by glueline failures. It wasn't the glue that was failing, it was acid byproducts of the decomposing glue weakening the adjacent timber. The aircraft was abandoned.
If you make it, you have to watch for development of acid afterwards. Given the amount of flour that some people dilute Cascamite with, without evident trouble, you may well be able to bulk up your casein glue with chalk whiting and buffer any acidity as it develops.
Lovely explanation, thanks. Still, rather a boat than a space ship. I wonder how the Cascamite people deal with the acidity problem. Alakaline additives as you suggest for the home made version?
I think they control the manufacturing process more carefully so there's little left behind that's going to decompose in the future.
That's a kludge - only suggested as such.
Well I shall give the kludge a whirl, the while pondering the technical prowess of the big boys. It's been an education. Thanks a lot for the helpful information.
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