Thin varnishes are a type of coating used to protect and decorate surfaces. The term 'thin varnishes' can refer to a variety of products, including SHELLACS, which are 8-letter solutions to the crossword. SHELLACS are a type of resin secreted by the female lac bug, which is native to India and Thailand. They are used as a wood finish, sealant, and primer, and are known for their glossy finish and durability.