Blackening Screws?

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Nothing stuffs up the appearance of a nice black anodized panel like a shiny zinc plated screw. Yes I know there are outfits that do the job, but the minimum charges are a killer. Any chemists out there able to share the secrets of the blackening process ?
cheers
M
 
mobyd said:
Nothing stuffs up the appearance of a nice black anodized panel like a shiny zinc plated screw. Yes I know there are outfits that do the job, but the minimum charges are a killer. Any chemists out there able to share the secrets of the blackening process ?
cheers
M

Machine and sheet metal screws are available with a black finish, just not as common as plated.

Jeff
 
richie00boy said:
Blackening is easy enough, here in the UK we use stuff called Metalblak, but I think you will have problems trying to black bright plated screws. You probably need to remove the plating first.

In the US, I have used Modern Masters brand "black patina aging solution" , and it works great. Richie00boy is correct, you need to remove the zinc with a short soak in acid. I use the common acid used for swimming pools (nitric?). Be real careful with this acid, it will burn and blind ! ....but with gloves and goggles, pour a tiny bit into a small plastic water-bottle cap, and soak the screw heads in it for about 5 minutes, until they turn grey. Wash off well, and dip them into the black patina solution, they will immediately blacken.
Remove them to air dry, don't wipe them.
Spray a shiny or matte clear lacquer on them.

=FB=

(or just go buy the pre-blackened ones)
 
Redrabbit's sounds the most promising so far.
First thing I'd suggest, since it's so easy you may as well give it a try anyway, is to head out to any auto parts vendor and get a can of something called "rust fix". Basically a pre-primer for rusty fenders. It's probably most popular among hillbillys that are waay too lazy to really work the rust off first and are really happy about a product that just turns the rust into black oxide.

I blackened a lot of furniture hardware/fittings with this stuff last year and was really impressed with the results. You've got to remove any plating first. It also helps if you expose the bare metal surface to the elements for a few days to get some surface rust going since this is actually what ends up constituting the "finish".

The brand my local parts store had was "Dupli-Color Rust Fix" in a 10.25oz spray can. It goes on clear and within an hour has turned the surface rust into a really durable, and very black, oxide coating that is naturally well bonded to the surface.

Most of what I used it on was basic old mild steel and the results were great. It might be less effective on high qualitiy screws, but you might want to try it anyway since it's so cheap and easy to find.

In any case, the method redrabbit suggested would almost certainly give a more uniform and fine grained appearance to something that was going on the front panel of your audio gear.
 
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