Increase open time in Hot Hide Glue preliminary experiment
Posted: Mon Feb 03, 2020 2:54 pm
I've done a preliminary and unscientific experiment, involving the addition of salt to hot hide glue, to increase working time. The result is encouraging. As a biochemist, I can design a better experiment with more controls, but as you can see, the addition of salt seems to work.
I used 1/2 cup of prepared 251 gram strength hide glue, in a 1:1 ground glue to water ratio. I heated the glue to 148° F.
Initially, I placed 1 drop of the glue between my clean index finger and thumb, opening and closing my fingers, feeling for tack while keeping time. I know this is subjective and my body temperature affects timing.
There was good tack at 36 seconds. It ended at 51 seconds. I repeated this 2x, with only a variation of 2 seconds. I also glued a piece of spruce to another piece of spruce at 50 seconds, which held. I tried it at 1 minute 5 seconds and it didn't. So, I think we can safely say that the working time for unadulterated hide glue is no longer than 1 minute.
I added 1/16 of a teaspoon of plain, non iodonized table salt to the pot and allowed it to stay at 148°F for 5 minutes, after mixing.
I repeated the experiment. This time, 1 drop of hide glue became tacky between my fingers at 1 minute 57 seconds.
The tack ended at 2 minutes 35 seconds.
I then placed the hot glue on a piece of Honduran mahogany. I clamped it to a piece of spruce after 2 minutes 35 seconds. 30 minutes later, the joint was holding without clamping, although not under stress.
I think it's safe to say that the addition of a small amount of salt increased the open time of hot hide glue by a factor of 2x, conservatively. I need to get equipment to measure the affect on the strength of the bond.
I used 1/2 cup of prepared 251 gram strength hide glue, in a 1:1 ground glue to water ratio. I heated the glue to 148° F.
Initially, I placed 1 drop of the glue between my clean index finger and thumb, opening and closing my fingers, feeling for tack while keeping time. I know this is subjective and my body temperature affects timing.
There was good tack at 36 seconds. It ended at 51 seconds. I repeated this 2x, with only a variation of 2 seconds. I also glued a piece of spruce to another piece of spruce at 50 seconds, which held. I tried it at 1 minute 5 seconds and it didn't. So, I think we can safely say that the working time for unadulterated hide glue is no longer than 1 minute.
I added 1/16 of a teaspoon of plain, non iodonized table salt to the pot and allowed it to stay at 148°F for 5 minutes, after mixing.
I repeated the experiment. This time, 1 drop of hide glue became tacky between my fingers at 1 minute 57 seconds.
The tack ended at 2 minutes 35 seconds.
I then placed the hot glue on a piece of Honduran mahogany. I clamped it to a piece of spruce after 2 minutes 35 seconds. 30 minutes later, the joint was holding without clamping, although not under stress.
I think it's safe to say that the addition of a small amount of salt increased the open time of hot hide glue by a factor of 2x, conservatively. I need to get equipment to measure the affect on the strength of the bond.