So I decided to venture into the world of hide glue, mainly to do some chair restoration because I suspect some of these older chairs might give out and I want reversibility. I'm familiar with the process having seen instrument makers do it before, but never done it myself.
I got a pack from Restorer's Choice and did some test runs. Gram weight 160-220, so not too high.
I can't seem to get the open time beyond 60 seconds.
I've watched all the youtube videos. Since this is a new experience, I'm fastidious with weights and temperature. I soaked the granules in 1 part glue to 2 part water by weight. I bring the glue to exactly 62-65 degrees C (142-145 F). I tried adding another part water (final ratio 1:3) to begin with. The open time is something close to 30 seconds. It was slightly cold that day ~15C/60F. So I try again, fresh batch, with ambient temperature ~20C/70F. This time, I begin with the same initial soak ratio of 1:2. I then gradually add more water to achieve a final heated ratio of 1:4, 1:5, 1:6 and 1:8. Even at 1:8 I'm getting an open time of at most, 60-80 seconds, depending on how thick I lay it on. Granted, at 1:4 it's roughly the consistency of maple syrup. But at 1:8 it's almost like a diluted water based paint. I also presume that glue strength will suffer at such low dilutions?
45-60 seconds is sufficient for a small simple join. It's probably not possible to do a chair with 3-4 joins that I need to brush glue on, align, push in, mallet and clamp. I'll need 3-4 minutes at best.
Am I missing something?
The other consideration is, and assuming my understanding is correct, since hide glue is water soluble and its entire reversibility revolves around the presence of heat and water. I noticed while playing around with the glue that a gelled portion of glue will easily be softened and stick to a fresh part of glue. So in theory, I could brush on most of the glue and do a final quick "wetting layer" and wack the pieces together quickly after that. Or alternatively I could just put it together and re-heat the joins with a hair dryer once they're together to get it to re-liquify. But these don't appear to be a standard process from videos and descriptions.
