vinegar or coffee works well with carbon steel. also bluing delivers good results. But the machine coating of stainless steel is a rather difficult process. For me, the solution lay in FeCl3 which gave a good result at the end:
The Mora Garberg is now available in carbon steel. I still like the stainless I have. The biggest issue I had was the handle grip was way too abrasive, so I just smeared it with JB Weld and sanded it down and painted it.
Have you tried Muriatic acid on Stainless Steel? I have been told it gives a good black finish. I have not followed thru and bought a bottle to check it out. I have some blades and gun pieces parts to check it on.
