Furniture Refinishing with Oxalic Acid

Because it’s easy to work with yet structurally sound, wood has been a favorite material for furniture makers for centuries. When newly made, your wood furniture item is clear, with an even sheen and color, but over time, the wood finish can age or fade. To remove old wood stain or other stains, you may apply an oxalic acid solution to the wood.

 

Oxalic Acid Solution

Oxalic acid, a form of organic dicarboxylic acid, comes from nature, although most brands today are synthetically reproduced in the lab. Oxalic acid is present naturally in some plants, including rhubarb and spinach. The oxalic acid you purchase for refinishing wood may be in crystal form and you will combine it with water before use.

 

How it Works

 

Oxalic acid acts as a bleach on wood, lifting away or lightening stains. Depending on the intensity of the stain, and how deeply it is embedded in the wood grain, more than one application of oxalic may be necessary.

When to Use an Oxalic Acid Solution

You may apply oxalic acid after you remove the old finish from the furniture. This usually involves applying a chemical stripper to the furniture or sanding away the wood finish. After combining oxalic acid crystals with water as directed on the package, you will brush the solution onto the bare wood and allow it to soak in.

Additional Information

The application of oxalic acid will swell and raise the grain of the wood, which can leave a rough feel.  After the furniture dries, you will sand it again to smooth the grain before applying a wood stain or wood finish.

Precautions

Wear chemical-proof rubber gloves and splash-proof eye protection when applying oxalic acid. Like all chemicals, keep oxalic acid out of the reach of children and contact a Poison Control Center in the case of accidental ingestion.