brown coat
brown coat — noun
1. In traditional three-coat plastering, the second layer applied over the scratch
In traditional three-coat plastering, the second layer applied over the scratch coat and underneath the finishing coat. It is usually brownish in colour because the sand and cement or lime give it that tone, and it serves as the main structural layer that creates a flat, level surface.
The contractors let the scratch coat dry overnight before applying the brown coat the next morning.
temporal sequence: scratch coat → brown coat
A plasterer keeps the brown coat evenly thick, about ten millimetres, to avoid cracks later.
collocation: brown coat + evenly thick / [measurement]
If the brown coat is too thin, the finishing coat may not bond to the surface properly.
The building inspector checked the brown coat for straightness before the finishers were allowed to start.
用法筆記
This term is almost exclusively used in discussions of traditional three-coat plastering systems. In modern construction, single-coat or two-coat systems are more common, so the word appears mainly in renovation or historic-building contexts.