Using Sur-Fin chemical on kitchen knives?

[Forrestcox]

I’ve heard lots about ferric chloride used on knives and kitchen knives to blacken them, but haven’t been able to find any information on a chemical I’ve been wanting to use to blacken stainless steel knives. The chemical I want to use to blacken my stainless knives is from Sur-fin company, Ni-black 40. It seams very similar to ferric chloride, but was curious if anyone else had any knowledge about possible heath concerns as I mainly want to use it to blacken and patina kitchen knives. It neutralizes with water like ferric chloride, but I want to make sure it won’t be an issue. I reached out to the company and got no response. I have no idea what is in the acid so I have no clue how to research it. I’ve heard lots of talk about how people wish they could blacken stainless and Sur-Fin chemical hasn’t ever come up in any research I’ve been able to find. They have other chemicals for blackening regular steel as well. I’ve used Ni-Black 40 for a stainless counter top used in the kitchen, and it produces a nice patina but I’m leary to use it on my kitchen knives. Maybe someone else is more knowledgeable on this than me or can drum up some information on it. Thanks

 

[scdub]

I couldn’t find any MSDS online but I’d expect that if I had it wouldn’t have helped much.
Most likely it would have said not to drink the stuff, but wouldn’t have addressed the safety of the patina itself.
I suspect that it’s safe, as it’s stuck to the steel and only trace amounts will ever be eaten, however it might be worth calling/emailing them directly:

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