NCIDQ IDFX Practice Exam

What type of coat is applied first in plaster construction?

1. Brown coat

2. Scratch coat

3. Finish coat

4. Second coat

The correct answer is: Scratch coat

In plaster construction, the initial layer applied is known as the scratch coat. This coat serves several essential purposes. First, it creates a solid base for subsequent layers of plaster by adhering to the underlying surface, often using a rough texture that allows for better bonding. The scratch coat is typically applied over metal lath or a similar substrate and is scored or scratched to enhance the mechanical bond with the next layer. The subsequent layers, such as the brown coat, are applied on top of the scratch coat. The brown coat smooths out the surface and provides a more even foundation, while the finish coat is the final layer, which adds a decorative appearance and is often smoother and more refined. Understanding these layers is crucial for ensuring a proper plaster application and achieving the desired finish in interior design projects.