scratch coat 打底灰泥层
Scratch coat \Scratch" coat`\
The first coat in plastering; -- called also {scratchwork}.
See {Pricking-up}.
Pricking-up \Prick"ing-up\, n. (Arch.)
The first coating of plaster in work of three coats upon
laths. Its surface is scratched once to form a better key for
the next coat. In the United States called {scratch coat}.
--Brande & C.