MULTI-PURPOSE: sorrel salt is ideal for whitening wood and textiles. It sobers and brightens the wood. It removes rust stains and deoxidizes metal and copper. 100% NATURAL: Starwax the Fabulous Sorrel Salt is also called Oxalic Acid. It is an odorless and colorless crystalline powder. It is composed of 99.5% pure mineral powder EASY TO USE: Sprinkle the rust stain with sorrel salt. Take a little multi-use stone using the sponge provided for this purpose, then rub. GREAT TIP: To sober up the wood: mix 200g of sorrel salt in 1L of hot water. Apply generously using a brush. Leave to act for approximately 2 hours. Scrub with a brush. Rinse thoroughly and allow to air dry. GREAT PERFORMANCE: At Starwax the Fabulous, we believe in the power of raw ingredients. We give credit to know-how, support the perfectionists of homemade products and share in the pride of getting the best possible results.