Need to remove rust stains from concrete steps. Stains caused by metal plates mounted into the top of each step, I suppose to prevent wear, when constructed some years ago.
Tried Iron-Out with scrub brish and finally wire brush, but it took an enormous amount of effort and didn’t give real great success.
Anyone have any ideas? Thanks.
Replies
Oxalic acid. That's probably what Iron-Out is, but a full service hardware store should have full strength, generic oxalic acid at a much better price. If not, look on line for McMaster-Carr or MSC.
Oxalic will work but it's very slow. You can saturate a rag with oxalic, lay it on the stain and cover with plastic so it has time to work. Phosphoric acid is much faster and stronger and won't eat the concrete like sulfuric acid does. If you use it you wear safety glasses and rubber gloves and don't breathe the vapors.
Guys, just curious if this same stuff will work on a white substance I have on my brick home? We have white siding (aluminum I believe; it's about 20 years old) on our second story and brick on the first story. Every couple years - on the south side of the home - the white sort of "washes" down on to the brick. I typically pay a guy $500 to powerwash it off but I'm getting tired of that.
Thanks, Rob
What you describe sounds more like paint oxidation(chalking) that is spilling over on the bricks. I don't think acid would work on a stain like that but a butyl detergent should do the trick. Check a local janitorial supply house for it. Brush it on, let it sit as long as possible and hose it off. If that doesn't work try automatic dishwasher detergent. Actually try the DW detergent first and maybe even wash the siding with it too. I've had great luck stopping aluminum from chalking by coating it with a good clear oil based paint sealer. It makes it look new and stops the chalking.
Don't use oxalic acid on aluminum -- it will eat right through it.
If your siding is chalking you need to clean it well and then paint it.