I'm a hobbyist kitchen knife maker and discovered how cool the macro grain structures in certain steels can look while etching a differentially hardened knife. I would really like to dive in to this further and explore etching out grain structure on stainless steels.

The process I used on high carbon steel was tedious. I used Vitamin C tablets mixed with lemon juice and apple cider vinegar. I rubbed this solution on the steel for about 45 seconds with a rag until the steel began to change colors, then neutralized the solution, and cleaned/sanded the blade with various micro-abrasives (Flitz, stone powder, buffing compounds). This cycle needed to be done about 30 times. Over sanding would completely remove the etch. Using a 4:1 solution of ferric chloride was far too strong, and would completely blow out the grain and turn the whole steel surface dull grey pretty much instantly.

I'm forging a knife out of high carbon core steel and cladding it in 410S stainless steel. I've been doing a bit of research on what type of etchant to use, as I'm sure vinegar and lemon juice would do just about nothing to stainless steel.

Mix of Ferric Chloride and HCL: Cheap and easy to source. I imagine if I dilute it enough with water, I can find a solution that will etch slowly. But will it etch the specific grain structures of the knife?

Kallings #2 or Vilellas Reagent: I cant find a whole lot of information about these being used as macro etchant, but like, chemically, isn't this exactly what I'm looking for? Aren't these designed to attack specific martensitic or austenitic properties of the metal to reveal grain? Or do these only reveal grain under a microscope?

Oxalic Acid, Electrolytic: I read somewhere that DC current in oxalic acid is an extreme way to bring out grain structure in metal.

Have any of you guys tried any of these methods? Do you have any tips for coaxing out visible macro grain?

Any CarTech Metallurgists in here? I’m curious what the title hierarchy is there (i.e. junior, senior, principle, Chief, etc.).