DRYLOK Etch cleans and etches concrete, stone, tile and brick. DRYLOK Etch removes efflorescence (salt-like deposits) and excess mortar. It’s perfect for etching concrete and galvanized surfaces prior to painting. Safer to use than muriatic acid. Clean and etch interior and exterior concrete, stone, tile galvanized metal and brick. Prepares smooth concrete for painting. Removes efflorescence. Cleans mortar from brick and tile. Conditions galvanized surfaces for painting. No harmful fumes, safer and easier than muriatic acid. Can be used indoors.