My journey began at the thrift store. I picked up a small $5.00 Rival Crock Pot. When I got home, I did some experimenting to see whether the "high" or "low" heat setting would give me my desired temperature. (A range from 120 - 150 is acceptable.) I found when the lid is on, it maintains about 140 on "high". Perfect.
Because I need the lid on to keep heat in, to slow evaporation of water, and to prevent glue from dripping into the water, I cut a hole in lid the diameter of the jar. Using the lid from my glass jar I traced out the shape.
I drilled a starter hole for my coping saw blade to slip through and then proceeded to cut it out.
I use the lid inverted so that the top of the jar sits up a bit proud for easy access. When heating, the jar lid rests on top.
To mix up the glue, mix equal proportions by volume hide glue granules and water. I ordered my glue from Jeff Jewitt at Homestead Finishing.
After about an hour or so, the granules should have soaked up most of the water and should look gelatinous.
It is at this point that you can place the jar in the crock pot with just enough water to match the level of glue and begin heating. (Make sure you don't put the jar directly on the bottom of the crockpot as it may crack the glass. I use a retired dish cloth for insulation.)
Once up to temperature, the glue should be the consistency of thick maple syrup. (Not the generic brand, I mean the real stuff.)
Plan out your glue-up and work quickly because you only have a few minutes of working time. Have fun!