A scratch coat is an essential step in DIY projects ranging from stucco applications on brick and stone to indoor plaster ceilings and walls. A scratch coats is easy to prep, apply and finish within a single day, so it's an ideal project for anyone with basic DIY experience.
What It Does
Scratch coats create a surface marked with lines and indentations that will grip the following coating and allow it to adhere properly. Because the scratch coat grips any plaster or composite material that is overlaid, it provides the perfect surface for a variety of projects, including plaster walls and ceilings that are crack- and chip-resistant.
How They're Made
When you make the first coating of plaster or composite material, you create scratches halfway through the drying process. Special tools are available, but a serrated knife or the edge of a trowel can be just as effective, as long as you apply the scratches evenly over the surface. The scratch coat needs to dry before you apply the second coat.
One of the great things about this coat is that because it will be covered in the finished project, the surface doesn't need to be perfectly even—just flat enough to corner off properly with the final coat and the room dimensions.