Oxalic acid is a popular choice for wood floor bleaching. Its properties make it effective at removing stains from the flooring without removing the natural colour of the wood. Although it is an acid and potentially toxic, with proper use it can be a safe and effective wood treatment. Knowing the proper way to use oxalic acid to treat your wood floors will help return them to their natural beauty while keeping you safe from harm.
Use a paint stripper to remove any paint, stain or sealant from the floors. Brush the stripper on and allow it to sit for the amount of time indicated on the packaging. Next, wipe the stripper away with an old rag. Wear a respiratory mask while working on the floors to prevent respiratory irritation.
Place 354ml of oxalic acid in either crystalline or powder form into a bucket. Add 1 gallon of hot water. Mix to combine. Wear protective clothing while working with the acid, including rubber gloves and eye protection.
Dip a mop into the acid mixture and use the mop to brush it into the flooring. You want the flooring wet, but not soaked. Leave the mixture undisturbed on the flooring until it dries completely.
Repeat Step 3, allowing the mixture to dry completely between applications, until the wood is all one colour. This may take one application or several, depending on the type of stain you are dealing with.
Place 1/2 cup of borax powder in a bucket. Add 1 gallon of hot water to the borax and mix to combine.
Dip a clean mop into the borax mixture and use the mop to brush it onto the flooring after your last application of oxalic bleach has dried. Leave it undisturbed until it dries completely.
Rinse your mop off in clean water and use it to mop up the borax. To make sure you removed all of the borax residue, wipe the flooring with a dark-coloured rag and look to see if there is any white residue on it. If so, mop the floor again with clean water. Allow your flooring to dry completely before restaining, painting or sealing the floor.
The borax works as an acid neutraliser, stopping the oxalic acid from continuing to work.