Question

I tried to get rid of some mild rust on a couple of steel elements (cases, screws and whatnot). My intention was to get rid of physical rust by manually scraping it off, perhaps sandblasting and then, with help of chemicals, to get rid of all traces difficult to reach by physical means.

Unfortunately, I haven't done my homework and I got myself a rust converter instead of rust remover. The former bases on phosphoric acid which turns rust into iron phosphate that results in black coating on steel elements that's supposed to be some form of rust protection, while the latter is supposed to physically decouple rust from steel.

To the point, now that I'm left with bunch of blackened elements, is there any solution in which I can soak those metal elements to get rid of this black iron phosphate coating (it not only leaves black traces on my fingers, it also stinks horribly) so that I can apply proper rust removal product (hopefully I'll get it right this time) and get those elements galvanised as I initially planned?

Answer 1

To remove the black iron phosphate coating, use a solution of diluted phosphoric acid. Wear protective gear and follow the instructions carefully. Afterward, proceed with rust removal and galvanization.

Step-by-step explanation:

To remove the black iron phosphate coating from your steel elements, you can use a solution of diluted phosphoric acid. Phosphoric acid is the same chemical used in the rust converter you mistakenly used.

However, you need to keep in mind that phosphoric acid is a corrosive substance and can be hazardous if not used properly. It is important to wear protective gloves and goggles when handling it, and to follow the instructions provided with the acid.

After removing the black coating, you can proceed with using a proper rust remover and then get those elements galvanized as you initially planned.