Oxalic acid's main applications include cleaning or bleaching, especially for the removal of rust (iron complexing agent). Its utility in rust removal agents is due to its forming a stable, water-soluble salt with ferric iron, ferrioxalate ion. Oxalic acid is an ingredient in some tooth whitening products.

irritate and burn the skin and eyes with possible eye damage. causing coughing, wheezing and/or shortness of breath. ► Exposure to Oxalic Acid can cause headache, dizziness, nausea and vomiting, convulsions, coma and even death.

Oxalic acid is widely used as an acid rinse in laundries, where it is effective in removing rust and ink stains because it converts most insoluble iron compounds into a soluble complex ion.

If the surface was veneer, sanding the stains out would be impossible. One of the most useful products in wood finishing that doesn't get a lot of attention is oxalic acid, often labeled wood bleach. It's useful for removing black water stains without changing the color of the wood.