Hello everyone, I have a problem with my board that I have never encountered before. I suspect that while doing some body work in my garage, some metal filings got on it and caused rust stains. Despite using iron out car wheel cleaner, the stains remain. Does anyone have any suggestions to fix this issue? Thank you.

I get the same thing on my white van, usually picks off with a fingernail. Maybe try picking it out with a sharp knife.

have you used a disc grinder on steel nearby?

Yes

Remove all the little bits. Not easy... but have to or it will recur

Use CLR to remove rust stains

Yes, a CLR soak for a few hours.

what is CLR?

www.bunnings.com.au/clr-1l-calcium-lime-rust-remover_p4460670

Could try Bowden's Three Way and claying rubber. Used them on a car with the same issue once and it worked pretty good. Other companies make similar products.