For removal/conversion of surface rust I also used the Home Depot phosphoric
acids. First Jasco "prep and prime". HD discontinued Jasco and now sells the
mentioned "Concrete Etcher & Rust Remover". There are a lot of resources
online on how to get the best results with phosphoric acids.
An eyeopener for me was PPG DX579 and DX520, again both based on phosphoric
acid but 2 completely different formulations. With DX579 I was able to
completely remove light "flash" rust from a previously media blasted panel. I
did a test first letting it sit for a couple minutes and then wipe it with a
clean towel, the towel was red-brown and the panel clean. The instructions
call for applying till the rinsing water sheets of the surface. This was then
followed by applying DX520 which leaves behind behind a zinc phosphate coating.
Although a bit more expensive these PPG products might be available in
Europe/Poland.
For heavier rust a 4.5-5" disc sander works great, 7" might be too big (and
heavy). Various abrasive wire wheels on a drill to get in the corners. It's a
dirty job though and best followed by a chemical treatment. As long as you
don't keep the sander on one spot too long there are no issues with heat. I
know people swearing by this method vs acid dip/media blasting. Doing my
gearbox cover soon this way!
Bert
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