In wood restoration where the acid dissolves away a layer of dry surface wood to expose fresh material underneath. Used many times on decks, docks and boats.
As an additive to automotive wheel cleaners.
Part of a mixture for pool cleaning.
As a mordant in dyeing processes. Vaporized oxalic acid, or a 6% solution of oxalic acid in sugar syrup, is used by some beekeepers as an insecticide against the parasitic Varroa mite.
As a rust remover in such applications as automotive shops, antiques restoration and various metals.