How do I turn stainless black?

[jmj3esq]

I have a set of stainless steel handle screws and nuts for a Spyderco Mule that I want to turn black. I dipped in ferric chloride and it only dulled the finish to a darker gray. I want them dark black though. How do I achieve this goal?

Here’s what I’m talking about.

 

[killgar]

There is a method commonly used on stainless steel hardware (nuts, bolts, etc) called "black oxide". It is achieved using a chemical called Ni-black 40.

I have a wide assortment of black oxide stainless steel hardware (purchased black, I didn't do it myself). It's reasonably durable, but can wear over time from repeated friction.

Google "black oxide patina". There are how-to videos on youtube.

You might also check to see if black hardware for that model of knife is already available, perhaps aftermarket, if you haven't already.

 

[SharpBits]

This thread from way back on Monday has details for you: https://www.bladeforums.com/threads/darken-stainless.1983952/#post-22576057

Edited to add that you might need to etch for longer or with higher strength. Otherwise, hit them with some Ceracoat or similar firearms type coating.

 

[badmatt]

See if there’s a local plating shop that does hot black oxide.

 

[Cementite]

If they're just nuts and screws, I'd be tempted to try heating them up and then dropping them into some drain oil. (This would probably ruin the temper of a knife blade, but probably wouldn't hurt nuts and screws.)

 

[navman]

Check out Caswell Plating Stainless steel blackening kit.