I understood that hide glue etc. was made from hoofs of animals.
In North America, hide glue is made from beef skins, other gelatin from pig skins. It can be made from a wide variety of animals including, rabbits, fish, and other innocent critters.
Any colour or links or howto ?
There are dozens of how-to videos on YouTube, but considering the last price I paid was a touch over $1.00 a pound including freight (OK, so it was 15 years ago), I doubt I'd ever want to bother. It keeps forever if it doesn't get wet, so I broke up a coupla fifty pound bags into small containers and tossed them up in the attic.
Resorcinol is supposed to need close fitting joints, and pressure, and then be pretty strong.
What about hide glue ?
It's more important to have close fitted joints with hide glue than with resorcinol.
I know it was widely used in the past and worked well, so it seems it was the "epoxy" or "araldite" or its times.
Hide glue has virtualy no cohesive strength, so it is absolutely NOT like epoxy, which cures by polymerization or other chemical reaction and becomes a solid strong mass. Hide glue hardens by evaporation only. In its hardened state it is brittle and crumbly.
Afaik, hide glue is heated, applied, the parts are pressed together, left, and next day you have a strong joint.
Is this right ?
Hide glue needs to be warm to be workable, and below about 95 degrees F, it doesn't stick to much of anything. Joints must be fully clamped before they cool below that temp. Clamp it too late, and the joint is near worthless by comparison. Lightly stressed wood joints can be "pressed" by hand, but there is a learning curve to the work, and it pays to know what you're doing. The literature often recommends about 100psi clamping pressure
The literature is on the stuff is mostly written for industry, and cautions like the heating temperature are based on glue pots under heat all day long. It CAN handle overheating (even boiling) for short periods, so some of us use it by heating in a microwave just before application. A quick blast of heat does no harm. We mix it with water, heat untli creamy, keep it refrigerated or frozen in little take-out hot sauce cups ready for use. Nuke it for a few seconds and it's ready to do a job.
There's lots to say about hide glue. . . .