In a three-coat plaster system, which coat primarily provides a smooth surface for the finish coat?

In a three-coat plaster system, which coat primarily provides a smooth surface for the finish coat?

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

Answer: (A)

The smooth, true surface for the finish coat comes from the brown coat. It’s the leveling layer, built up to fill irregularities from the rough scratch coat and to create a flat plane. After it’s floated and set, the finish coat is applied in a thin layer on top to achieve the final surface. The scratch coat is intentionally rough to key the next layer, and the finish coat sits on this smooth base, not the rough surface of the scratch coat. In this system, the brown coat is the one whose primary job is to provide that smooth base for the finish coat.

The smooth, true surface for the finish coat comes from the brown coat. It’s the leveling layer, built up to fill irregularities from the rough scratch coat and to create a flat plane. After it’s floated and set, the finish coat is applied in a thin layer on top to achieve the final surface. The scratch coat is intentionally rough to key the next layer, and the finish coat sits on this smooth base, not the rough surface of the scratch coat. In this system, the brown coat is the one whose primary job is to provide that smooth base for the finish coat.