Hide glue has been around for centuries, and had the ability to adhere to already existing glue, making it ideal for restoration. When restoring furniture, ideally it is good to remove as much existing glue and residue as possible, however if this is not possible, it is not the end of the world.
Using heat and water to transform the beads into a liquid, traditionally in a double boiler or urn, the mixture will need to be heated to approx. 80°C into a thick broth consistency. Because it is heated, it will cool quickly so you will need to work quickly, painting it onto joint before clamping. Curing time can be lengthened by adding extra water into the mixture, or heating the joint prior to glue up. Setting times will be less due to the cooling times as well.
This is the sort of glue that once you start using it, it will become a favourite and used regularly.