The animal glue is used in the various gluing machines like the
SLine-GL.
This type of machines has the job to spread a costant film of glue on the sheet of paper.
It has a specific section in it, the glue tub.
That section has the job to prepare the mixture of glue and water to be deady for the spreading.
This means that the animal glue has to be melt and mixed with hot water.
By changing the percentage of water in the glue and the temperature, the machine can regulate by its own the viscosity
of the adhesive to match the specification of the glue and the need of the materials.