I created my own hid glue from rawhide chews that my dog Zoë rejected. Rather than let them go to waste, I decided to try my hand at this ancient form of glue making!
I submerged pieces of dry rawhide in rainwater within a small crockpot and I proceeded to render the rawhides for three days. This should be done in a well ventilated area, the glue has a very distinct smell that can become overwhelming if not allowed to escape through an open window.
After three days, the rawhide pieces fully disintegrated into the liquid and the consistency became thicker (much like runny gravy). At this point, I proceeded to reduce the liquid in a shallow pan over the stove till the liquid was a more glue-like consistency.
After reducing the liquid, I poured the glue into an aluminum casserole pan and allowed the glue to dry into sheets, flipping them over to allow thorough drying.
Once the glue was completely dry, I roughly pulverized the sheets into shards of glue and stored them in an airtight glass jar.
To use the glue, a small amount of (ideally hot) water is added to the glue shards to reconstitute the adhesive. This process was very rewarding and I am very pleased with the quality of the glue I made!