rust remover

[bob]

hi all,i put rust remover on some galvanised metal and it worked a treat,i washed it with soapy water but now it has dried there is patches of white powder,is there anything i can use to halt the reactin continuing,many thanks

[NT]

rust remover tends to be phosphoric acid, so baking soda or washing soda.

NT

[spamlet]

Usually phosphates, but they create a passive 'ready oxidised' surface (If you are really brave, you can get an even more passive finish - but not on your zinc coated stuff I suspect - with fuming nitric acid. It is quite a surprise to dunk some iron into this and not have it instantly froth up.)

Trouble is, if you succeed in washing it off, it'll probably rust again. On the other hand, leave it, and the paint doesn't stick properly. In the end I used to find that, 'red lead' straight on the cleaned metal was the most effective preparation.

(Also note that with the typical dimpled 'Hammerite' finish, there is nearly always a little 'fish-eye' of uncoated metal, that rusts. Used to try all sorts of additives to prevent the dimples developing into fish-eyes, but rarely managed it, so smooth is best if you want rust resistance.)

S

[Jim K]

I find 2 coats (as per destructions) covers 99.9% satisfactorily...

cheers Jim K