Glue – A system where both coats are made of animal glue is used when the strength of the bond is not an important factor, such as with lightweight papers and materials.
Phenolic Resin – This system uses full phenolic resin for both coats. It is designed to withstand moisture and heat during application and is the most durable adhesion available.
Resin over Glue – A system where the make coat is animal glue, and the size coat is either urea or phenolic resin. It is used when more strength and heat resistance is necessary.
Urea Resin – Both coats are resin-based in this system. Urea resin withstands more frictional heat than normal glue adhesives, but not as much extreme heat as phenolic resin.
Grit type is either aluminum oxide (white, pink, ruby red, brown, grey, etc.) silicon carbide (black or green), ceramic (blue and pink) or any combination of these. Grit types are sometimes mixed in combination for achieving certain cutting characteristics.