Removing galvanising from small parts chemically?

[julianf]

In the past ive just soaked them in a conc. NaOH solution.

Last night, i had no NaOH, so went to KOH, which, i would assume, would do the same.

I dont understand why, but it made no difference over night at all.

Either my KOH has gone off, or the coating is not what i think it is, or "something else".


Ive got some 85% phosphoric about too. Before i just start throwing it about, it looks like the chemistry will work (ie it will strip the zinc) but what sort of rate should i expect?

Are we talking a 20min job, overnight, or the rest of the week?

Thank you.

 

[Seadog]

It'll probably strip it in a couple of hours tops. It obviously depends on the coating thickness.

 

[Kram]

Both should work, zinc displaces the hydrogen to make potassium zincate or sodium zincate.

 

[frank horton]

we used brick acid to clean and give a good surface for paint on corrogated sheeting

 

[Hopefuldave]

Brick acid (the strong stuff) will strip it in seconds, wear rubber gloves and a face shield, stay upwind, outdoors, as the fumes are *nasty".

Dave H. (the other one)