It’s found in cabbage, broccoli, Brussels sprouts, sorrel, parsley, and in the Virginia creeper. But in the highest concentrations (still only half a percent, but enough to make the leaves poisonous), it’s found in rhubarb plants.
I am speaking about oxalic acid, a 100% natural product that, however, is also often produced artificially in a laboratory. In fact, over
Remove iron stains 120,000 tons of this very useful acid are produced annually worldwide, and chances are, you can put it to practical use in your home renovation project.
Oxalic acid is a colorless crystalline solid that has the chemical makeup C2 H2 O4 – two parts Carbon, two parts Hydrogen, and four parts Oxygen. When its crystals are diluted into water, the resulting solution can be used for such diverse purposes as:
- Extractive metallurgy (a metal manufacturing process.)
- Dyeing textiles – as an aid in helping the dye set into the fabric.
- Bleaching pulpwood.
- An additive in baking powder.
- Protecting marble surfaces and “making them shine.”
- Removing iron or manganese blemishes from slabs of quartz.
But the most likely way for a homeowner to utilize oxalic acid is in cleaning up old furniture and other stained wood products in your home. Visit the Real Milk Paint website by clicking the link to find top of market products that can clean rust stains off of wood!
How To Remove Rust Stains From Wood With Oxalic Acid
Anytime metal is in contact with wood for extended periods of time, there’s the risk the wood may get moist or water may get on the metal or between the metal and the wood. Oxidation sets in. Rust marks get left on the wood surface, often times being rather deeply ingrained.
You’ve scrubbed and scrubbed and tried other cleaning products, but those stubborn rust stains won’t come off the wood. What now? Get a cleaning product that contains oxalic acid, and it will likely all come out.
But first of all, make sure it’s really a rust stain. Iron oxide stains consist of dissolved iron particles that have chemically bound themselves to wood, in the presence of water. These stains are usually black or very dark brown.
Carefully identify the stain because if it’s a red stain or if it’s a black ink stain – oxalic acid won’t get it out. Those other stains may need to be bleached or sanded down instead.
Next, if your wood is coated with polyurethane, understand you have to remove the protective coating to treat the wood because the rust stain is below the coating.
Mix a tablespoon or two of oxalic acid (follow the specific product manufacturer’s recommendations) with a small amount of water to form a paste. You don’t want it too wet – it doesn’t need to “soak in” but only sit on the surface to do its work.
Use a brush or cloth to apply the oxalic acid to the stained area(s) and watch while the paste turns yellow. After 15 to 30 minutes, scrape off the paste and brush or vacuum away the debris.
What Kind of Results Should I See?
If you don’t see a significant difference after a single application of oxalic acid paste to the rust stain, then it’s probably not really a rust stain. Try something else.
But you may often see a big difference, and yet, the sain isn’t yet 100% gone. Don’t despair. Many times, it takes 2 or 3 applications of oxalic acid to fully remove a deep, stubborn stain. A lighter stain may come up after just one application, on the other hand.
Oxalic acid is a key tool for anyone wanting to save an antique or special piece of wood furniture that has been badly stained by contact with iron. It almost always gets the stain out, though it may require multiple applications and a little elbow grease and good old fashioned patience to get it done.