by soaking in black coffee?

I saw this on a video last week. Never seen or heard of this method before.

Anyone here at all familiar with this process?

High carbon you can etch, for stainless it won't work. If I want to dark etch damascus, I boil 1 jar of instant coffee with about a quart of water. Let is soak about 2 hours but you can soak longer if you want. It will come out like this

That’s gorgeous! Thanks for the reply. The video was making a tomahawk from, iirc, 4140.

Ferric Chloride works real well to etch. I just procured a bottle of it from Frigid North last week and did some playing with it today. It works good, and fast!

The video I saw, was just turning the tomahawk head black. There was no pattern nor Damascus they were trying to etch, per se. It was just coloring the head.

It’s the same as using vinegar or lemon juice to force a patina. The acid in the coffee attacks the surface of the steel.

At least that’s my understanding it.

Have you tried it? I’ve only used vinegar for rust removal. (Other than cooking)

I have not yet. It’s on my list of things to play around with at some point. Mainly I’ve heard/seen it used to display the pattern on Damascus as demonstrated by that beautiful knife dan308 posted. The high nickel alloys don’t take the color and gives you the contrast. Supposedly the coffee really makes the 1084 or whatever your using dark, even more so than the ferric chloride.

I’ve used vinegar, lemon juice, onions, etc but for my purposes cold blueing works best so far. I’ve made some pretty dark too.

I've had good success with Birchwood Super Blue. The same stuff I use to touch up firearms. It is a solution formulated to do exactly what you seek.

Active ingredient, Selenium Dioxide

Did find a little info here.

https://www.iforgeiron.com/topic/47031-etching-with-coffee/

Think I’ll use the cold blue.

Re-found the original vid I referenced and it was Damascus, not bare steel.