SPEC MIX What is Scratch and Brown? what is a brown coat.

What is a scratch coat?

Definition of scratch coat : the first coat applied in plastering having lines scratched on its surface to improve the bond with the next coat. — called also first coat.

What is scratch coat used for?

A thin mortar bed for use as an underlayment providing a sound, stable surface for bonding ceramic tile over Exterior Grade Plywood.