Put 1 part powdered hide glue and 2 parts water into a jar. The picture below shows the water and powder mixed on the left, sitting next to a jar of dry hide glue powder on the right
Let it soak for an hour, to take up the water.
It becomes much thicker and more rigid, on soaking up the water.
To use this glue, it is recommended that you stir the granules and leave them overnight. Then, you can warm the glue up to a liquid state, using a glue pot or gentle heat in a double boiler. In a sealed jar, this glue can last a couple of weeks, at least. It is water soluble and can be reheated to return it to a liquid state, even when on a project.
This is what the rehydrated glue looks like, before being heated to a liquid state. The volume shown is 3 teaspoons of dry size and 6 teaspoons of water. It is the same volume in the picture to the left and the jar on the left in the image above. The expanded size has been stirred and chopped up with the plastic knife shown on the left, making it fluffier. Hence, it appears larger.
This will be heated and painted on to the leather crest shape in 2 - 3 layers before the gesso layers are added.
