Hardness for black chroming

I'm a chroming shop owner we just made a bath for black chroming the chemical we use is of course chromic acid, barium and acetic acid ⇦ on eBay or Amazon [affil link] and distilled water we use stainless steel anode the problem is the hardness of course it turns the metal to black but it just fades when we rub it slightly. Is there any process to make it hard?

You should be using lead anodes (pre-treated with a weak sulfuric electrolyte to form a coating of lead peroxide).
I use a similar black chrome solution, over bright nickel, over copper, on steel parts - including stainless. The result is a durable finish in shades of dark grey through dark brown to almost jet black, dependent upon temperature and current used. After plating, I lightly oil the parts to give a hint of blue, very similar to the blue/black on shotguns, rifles, etc.
Good luck