Ferric Chrolide on knurled chrome knobs

Hi. heres a problem. i tried using the fume method with Ferric Chrolide on these knobs to no effect. i ended up bathing them in it. i also used a 240 sand paper. it ate straight through the top of the knob revealing the copper. however it has had no effect on the knurled sided. does any one know why and what i can do about it. id really like to get that dirty effect like the genuine pair onthe bottom. cheers

Use 'em for a few decades? :wink:

dont have that long

Hmmm, that is a problem. I'm not getting any younger either.
Why not try tumbling them in something gritty, like dirt and motor oil?

you could use a "wash" of flat black model paint, it is a common detailing technique.

You can look it up, of course, but basically you thin some black paint, brush it into the knurling, then wait a mintue or so, then wipe off the high spots.

Why not try tumbling them in something gritty, like dirt and motor oil?
I'd rather not have my knobs coated in carcinogens.

Umm, he can wipe it off afterwards.

PS, ever check out what's in chrome? :wink:

PCB Etchant solution ( computer board etchant solution) available at Radio Shack, it will artificially age nickel on contact, but needs to soak a while on chrome.

On chrome, It helps to put the parts in a bucket with rocks and shake the hell out it first.

I have a lapidary vibratory tumbler, and chrome plating, as hard as it is would need ceramic cones to break it down. I don't hand engraver through chrome plating because it spalls (like flakes of shale) and destroys the surrounding areas. Nickel plating is engravable, so it's less tenacious.

http://www.youtube.com/watch?v=AoA0O6kSBqk

Found that on the Stratocaster Forum - he uses muriatic acid in a sealed container - just the fumes mind you. Do it in the out of doors only - fumes can be toxic!!

PCB Etchant solution ( computer board etchant solution) available at Radio Shack, it will artificially age nickel on contact, but needs to soak a while on chrome.

On chrome, It helps to put the parts in a bucket with rocks and shake the hell out it first.

isnt that the same thing lol

Ive tried all the above. im just not gettong good results with acid

isnt that the same thing lol

It's one of the more common PC board etchants, yes, but as noted above, chrome is very tough, and does not react like nickel.

A very strong chlorine bath will eventually attack the chrome, especially if kept hot. Not sure how long it will take. I always refer my relicing work to the undisputed specialist in the world: Old Man Time.

EDIT: After reviewing the photo of the effect you're after, I'd have to say your best bet would be the flat black model paint technique mentioned above. Also, one of the problems you've had may be that your knobs need to be degreased, no matter what method you use. Acetone would be good for that.

I'd say try muriatic acid fumes, or get a pair of nickel knobs and try again.