Oxalic acid is a key ingredient in several commercial cleaning products that announce its suitability for cleaning the grout. Care needs to be taken when using these products as oxalic acid can actually damage granite and marble, metal oxide fittings and corrode grout if used too often and not rinsed properly. As a last resort, however, and with proper precautions, oxalic acid can be particularly useful in the restoration of grout stained by lime and rust.
Instructions
1 Make a paste the consistency of peanut butter with an oxalic acid cleaner, as a friend of the Guardian bar, and water. With thinner cleaners, you will need to gently apply the undiluted solution over the grout with a rag. Although oxalic acid is less corrosive than lye, you should still wear gloves when working with it.
2 wet grout and tiles surround before applying oxalic acid cleaning compound.
3 Rub the cleaning paste into the grout between the tiles. Let stand for no more than a minute or two, especially if you are working with marble or granite. Oxalic acid creates a suspension of acid on the surface of the grout or some stone tiles. This dissolves the superficial stains that have joined with the grout.
4 Clean the areas around the grout to avoid damaging the tiles, especially stone tiles. Clean with large circular motions, especially with stone tiles such as oxalic acid will have a surrounding tile polishing effect. Large strokes even effect and help prevent blotching from grout. Several times rinse thoroughly, dry the surface with towels to remove all cleaning product.
5 seal the grout with a grout sealant according to the manufacturer's instructions. The sealant will help preserve the restored grout color and help prevent having to use this cleaning strategy too often. Excessive use of oxalic cleaning products can result in blotching of grout as acid corrodes grout surface over time. Penetrating sealant works better than topical sealants and needs to be re-applied annually to maintain protection.
Tips and warnings
- Oxalic acid Cleaners can also remove metal accessory oxide as well, using the same cleaning precautions.
- Oxalic acid is found in foods such as spinach and is a more natural cleaning agent than many other chemicals on the market. However, because of its concentration, oxalic acid should be treated with the same care and respect with which it would bleach or muriatic acid.
- Oxalic acid corrodes limestone and similar minerals. That's one reason it works so well and another reason why it should only be used as a last resort.
- Always wear eye and hand protection when working with cleaning chemicals.
- Test the tiles first with a mild acid in a non-visible area to ensure that the cleaner will not damage the tiles.
- Do not mix oxalic acid products with other cleaning products to prevent the release of toxic vapors.
- Do not use oxalic acid cleaners in gold, silver, tin, marble, lacquered metals, or anodized aluminum.