chrome removal ?

[scotty]

Can any wise chaps out there advise on the best way to have chrome removed without damaging the metal to much ?

I've got a fully enclosed chain guard that was chromed by a PO that I'd like to return to black.

Any thoughts appreciated

Cheers

S

[muskrat]

Any chrome plater can un-chrome it. Same operation as chroming but in reverse.
Cheers

[Brian]

You can paint or powder coat over the top of chrome so there is no real need to strip the chrome off.

[kiwipom]

Hi guys, as far as I know : caustic soda/spirits of salts(hydrochloric acid) will do it, cheers

[morris]

It can be done chemically but don't try it yourself. The vapours of the chemical chromium removing process are extremely poisonous.
Best thing to do is to take it to a chrome plater as Musky suggested.
Or just have it painted over. Perfectly possible.

[Greybeard]

Petrol tanks have to be chromed all over before painting. I think a special primer, maybe etching primer is needed to make a suitable surface for painting.

[u28909z]

I dechromed a side stand using battery acid and a battery charger. The chrome was removed in a few minutes, but the nickel under the chrome is untouched.
I probably wouldn't do it again, or recommend anyone else to do it, as the fumes produced were very unpleasant, and likely very toxic.
Paint seems to adhere well to the dull nickel left when the chrome has gone.

[jachenbach]

As noted above, you don't actually have to remove the chrome (unless it's peeling). All you really need is to roughen the surface to give the paint some "bite". I do it in an abrasive blasting cabinet. You can also rough it up with emery cloth. Just to be sure, I also use a self etching primer.

[scotty]

Thanks for the replies everyone

I think I will scuff, suitably prime and paint
cheers

S

[coater87]

 After talking to many pretty good painters here, they all recommended epoxy primer. I was kind of surprised thinking self etch was the key, but most agreed self etch is not as good on chrome as epoxy.

 I guess the term "self-etch" lulls people into believing it will etch into chrome.

 It sounds like they use 36 grit grinding discs (and all warned me about heat warping the metal- keep it moving and short, short grinding bursts) to tooth the chrome really well, then scrub down with wax and grease remover, then epoxy. Then 80 grit the epoxy (but dont break through) followed up with a sealer, then high build primer over that. Then its block sand and paint/clear coat.

 I have painted cars in the way back, when things were easier (fewer steps, fewer choices). Now it sounds like there are 5-7 steps, with 10 to 20 choices for each step, and one bad choice can ruin the job. Pretty confusing really.

 (but the paint jobs of today are spectacular compared to 30 or more years ago!)

[nimrod650]

a leaking battery has stripped many chainguards and silencers of  chrome

[East_Coast_BSA]

a leaking battery has stripped many chainguards and silencers of  chrome

Sliding on the pavement does an admirable job too.

[Dean]

Cola or tea will remove chrome (you have been warned) which is usually just a flash covering over the bright nickel, but it takes more to remove the heavier nickel and possibly copper coats beneath. You could etch these off by suspendinh the parts in acid and passing a current through as we used to when i worked in the trade. The only downside is that if you breathe the fumes you will die.

[BSA_54A10]

Chrome is very soluable in sulphuric acid.
Chromic acid is basically chrome dissolved into sulphuric acid.
Nickel is only sparingly soluable in sulphuric acid but is very soluable in hydrochloric or nitric acid.