Recommendation? San Mai Etching Weirdly

[Stark Knives]

I recently got some 52100 core with a 410SS jacket and got some odd results when I went to etch it. Both of the steels etched very gray and the core did not seem to blacken very well (first picture). Normally when I use steel like this the core gets super black and the stainless jacket doesn't etch at all and remains shiny (second picture). Does anyone have any idea of what could be causing this? It still looks cool, but it is not what I was expecting to see.

I had it professionally heat treated by Bos heat treating to 60-61 RC and they said they weren't sure what could be causing it. I made sure to degrease the blade and etched in ferric chloride (both my normal solution and a fresh one to see if that was the problem).

Let me know if there are any other variables or ideas you could think of and thanks!

 

[weo]

How much grinding did you have to do after HT?

 

[Stark Knives]

How much grinding did you have to do after HT?

I did a pretty decent amount, not like from full thickness to finished after HT, but the edge was probably at least .05" thick I'd say. I was also thinking it could be scale but I thought I ground past it pretty well. I have a couple of chef's knives in the same steel that I could try out. On those I haven't done any pre-HT grinding.

 

[Stacy E. Apelt - Bladesmith]

Some thoughts:
1) Test the FC on a hardened piece of the 52100 and see what happens.
2) If you polished it before the etch - resand it with 400 grit and clean it really well with dish soap and hot water (or use TSP), then try again. ( try it even if you didn't polish it)

 

[Stark Knives]

Some thoughts:
1) Test the FC on a hardened piece of the 52100 and see what happens.
2) If you polished it before the etch - resand it with 400 grit and clean it really well with dish soap and hot water (or use TSP), then try again. ( try it even if you didn't polish it)

Thanks for the stuff to try! I'll give it a go this weekend.