After removing the parabola from the predecessor, traces of rust, I think, appear at this location and below like "dripping" on the projected plaster dating back 3 years. How can I remove these marks without damaging the media?
Use a special product such as "Rust Stain Remover" from ALGIMOUSS. Do not forget to protect yourself because the product is corrosive: gloves and goggles mandatory.
Moisten the substrate then apply the pure product with a brush, leave for 45 minutes, rinse and rub with a brush.
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