2019年6月15日 · The iron in the tap water reacted with the tannins in the wood and caused dark spots to appear all over the wood (doh!) I’ve tried oxalic acid to remove the stains, which worked beautifully. However, when I went to neutralize the acid (with a mixture of borax and distilled water), the mixture began turning dark and caused a lot of the stains ...

1999年8月29日 · *Here's a slightly different take on Oxalic acid.I refinish / repair / restore a lot of furniture, and Oxalic acid is the first thing I reach for to take out black water stains and weathering. I use other methods too but oxalic takes care of 75% of what I run into.I mix about 3/4 pound of crystals to a gallon of HOT water (3 oz to a quart), and ...

2008年1月20日 · The Black Stains that occur close to the metal in a gun stocks, or any other piece of wood/steel that gets wet, are almost certainly from the reaction of the Tannic Acid, occurring to varying levels in most woods, with the Iron Oxides (rust). It can be removed with Oxalic Acid. It forms a chemical complex, dissolving the rust/Tannin compounds.

2018年10月10日 · Start by sprinkling the oxalic acid powder over the stained area. Then use the toothbrush dipped in water to turn the powder into a paste. Scrub the paste gently over the stained areas. Let the paste sit on the wood for 30 minutes or so, until most of the water has evaporated and the paste has turned into a white crust.

2021年7月11日 · I tried using oxalic acid to lighten the spots, but no luck. I’ve seen people say mineral spirits, but that also did nothing (I’ve never had any luck using mineral spirits to clean up CitiStrip). I’ve sanded the wood but the blotches seem too deep to get out with sanding.

2023年1月25日 · Although oxalic acid is relatively safe, if one is not familiar with using it needs to be aware it is a mucus membrane irritant. You will notice it most when sanding the dry wood after the treatment has dried. If you wipe down the treated area with a damp cloth, you can remove most of the dissolved crystals.

2021年5月21日 · Then I applied an oxalic acid wash to remove the black stains – which worked really well. Next I did the final sanding with 220 grit. Then I applied two coats of clear gloss polyurethane using a brush, finally spraying on two coats of satin polyurethane. This looked great!

2020年4月1日 · Oxalic acid is wood bleach, and is used to remove the black marks from glue up reaction to glue and steel clamps. Works with no damage to surrounding wood. Have not needed any since using tiny spacers to keep the clamps from touching the glue during glue up. You only need a tiny bit, enough to wet the surface of the stain.

2009年1月23日 · If you use oxalic acid; mix it into warm water. You can apply it to the ring with a small brush to keep it localized. You'll find it will probably need to be done a couple of times to get the proper results. If you are able to get it to lighten up, you'll see that it is now an eyesore in a …

2001年7月15日 · Sounds like the teak is dirty. Go to a marine supply store and purchase a "teak cleaner". Most will have oxalic acid as their base. Apply it per the container instructions and brush it in with a stiff nylon or brass bristled brush. Two part bleach is used on wood to take the color out of wood. It doesn't clean the surface.