In standard three coat plaster applications, what is the second coat referred to?

In standard three coat plaster applications, the second coat is referred to as the brown coat. This layer is applied over the initial scratch coat, which is the first layer designed to create a key for the subsequent layers. The brown coat serves multiple purposes: it helps to create an even surface for the final finish coat, provides a thicker layer for better durability, and allows for the establishment of a smoother finish.

The brown coat is typically left somewhat rough to provide an adequate bonding surface for the finish coat that follows. This is crucial for ensuring that the final layer adheres well and presents a smooth appearance. The term "brown coat" can also originate from the color of the sand and lime mixture used, which can appear darker compared to the scratch coat.

Understanding the role of each coat in the plastering process is important for achieving the desired finish and structural integrity in plaster applications.