In reply to Post #1
Keep 30 years then your b rich

In reply to Post #16
ferric chloride can be an option.
Did lot of parts on knives with it, like the blades, screws and pocket clips.
But it only turns the metal dark grey, like fine sandblasted.
There you go. Next option, sand blasting

In reply to Post #3
Can you not use engineers cold blueing liquid on it ? Is that the chemical that's already been mentioned ? You just paint it on

In reply to Post #18
I have tried that and it didn't do a thing

In reply to Post #18
You can put that on tool steel, like some knife blades that are not stainless.
Everything that has chromium in it will show nothing.

In reply to Post #1
If money is no object it is possible to black chromium plate directly on to the stainless steel. Or nickel plate it first and black chrome over this.
I black chrome plated some stainless bank sticks many years ago and they went well.
However, as mentioned it would work out very expensive. Better to get them etch primed and powder coated black I would say. Or sell it and buy black anodised aluminium.
You can blacken stainless steel using harsh chemicals and direct heat but the finish wouldn't last long.