Definition of scratch coat in English:

scratch coat


North American
  • A rough coating of plaster scratched before it is quite dry to ensure the adherence of the next coat.

    • ‘On smaller buildings, I combine the slip and scratch coats by making one sloppy, high clay-content plaster and mush that directly into the bales.’
    • ‘After it becomes tacky, the first scratch coat of polymer cement is applied.’
    • ‘A typical historic plaster system is made out of three coats: a base or scratch coat, a brown coat, and a finish coat which contains less sand and gives the wall its smooth finish.’
    • ‘First, a scratch coat is troweled onto the lath; the plaster oozes through the lath and grips the backing when it hardens.’
    • ‘Mix and apply slurry coat to the existing scratch coat ahead of the render application ensuring that the render is squeezed into the wet slurry coat.’