Which coat is applied immediately after the bonding coat in the typical plastering sequence?

Which coat is applied immediately after the bonding coat in the typical plastering sequence?

• A. Finish coat
• B. Brown coat
• C. Scratch coat
• D. Cure

Answer: (C)

The first layer after a bonding coat is the scratch coat. In plastering, the bonding coat sticks to the substrate, but it needs a rough, keyable surface for the next layer to grab onto. The scratch coat provides that key by giving a rough, irregular surface that the subsequent coats can adhere to more securely. After the scratch coat is applied (and scored or scratched to create the key), the brown coat is built up for thickness and final shaping, and the finish coat then provides the final smooth surface. The cure stage isn’t a coat in the plastering sequence.

The first layer after a bonding coat is the scratch coat. In plastering, the bonding coat sticks to the substrate, but it needs a rough, keyable surface for the next layer to grab onto. The scratch coat provides that key by giving a rough, irregular surface that the subsequent coats can adhere to more securely. After the scratch coat is applied (and scored or scratched to create the key), the brown coat is built up for thickness and final shaping, and the finish coat then provides the final smooth surface. The cure stage isn’t a coat in the plastering sequence.