If you are going to stick stuff together then you are going to need glue. Here are two ways to make glue from animal byproducts.
Hide Glue
1) Scrape or sand dried rawhide and collect the dust. The smaller, the better, but you could chop it into small pieces.
2) Make sure the hide is defleshed, and clean off as much dirt and grime as possible.
3) Add to a pot with hot water and simmer (just below a boil) forever. At least 24 hours, maybe 36 hours. Keep topping off with water.
4) When you have a honey-colored syrup, strain out any remaining dirt and undissolved bits of hide with cheesecloth.
5) Return the filtered liquid to heat, and simmer it down to the consistency of honey, or maybe a bit thicker. Commercial plants keep this mixture at 160F for this stage, and use a vacuum to help evaporate the excess water off. Do not let it boil – the glue will be ruined.
6) pour the thickened mixture into a pan, and allow it to cool away from sunlight.
7) Once the mixture gels, remove it from the pan and cut into thin squares. It should be the consistency of really, really thick jell-o.
Run a string through the squares and allow to dry away from any sunlight. The resulting flakes last forever if kept away from any moisture and sunlight.
9) To reconstitute the glue, add the flakes to a little water and heat to 140F. It should be the consistency of pasty-honey. keep the glue at that temperature to use it. They used to use glue-pots for just this purpose.
Fish Glue
1) Collect a bunch of fish scales. Rinse them about a billion times to remove any fish smell from them. If you don’t the stink will be unbearable. 12oz of scales makes a couple of ounces of glue.
2) In a sealed, heatproof container, cover the scales with water.
3) Toss the sealed container into a pot of boiling water. Make sure the container doesn’t let water into the container.
4) Allow the scales to boil, then cook on low heat for 6-8 hours.
5) the scales should have dissolved, giving you a clear, strong glue. Keep cool in a sealed container when not in use.
Working with Animal Glues
- Keep your joints tight. These glues have no gap-filling properties.
- Hide glue needs to be kept at 140F while working with it. When done, allow to cool and just re-heat to continue. You might have to add a little water every now and then to the glue pot.
- Open time for these glues is about a minute – plan your glue-ups accordingly, and use dry runs to make sure you can pull it off.
- An advantage to hide glue is you do not need a lot of clamping power. The glue naturally pulls the joint tighter.
- Fish glue is thinner and less sticky than hide glue.
- Both glues have poor moisture resistance, use a wax to protect it.
- The strength of the glue can vary widely. The temperature used to cook down and the amount of water used to reconstitute are the primary factors.
Hide glue can be purchased in granules and kept indefinitely. Five pounds of crystals sell for ~$35. All other woodworking glues have very short shelf lives. Urea formaldehyde and yellow woodworking glues lose their strength after a year. I’ve stored yellow glue carefully, and managed to squeak it out to the two year mark. I have not had much luck with CA glues – they go bad after 6 months once opened. storing the sealed containers in the freezer does extend the CA glue’s life.
Hopefully this helps! As always please contribute by adding comments or an e-mail.
