Making Damascus Black Etch Permanent in the Kitchen

Michael Kemp

Michael Kemp

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Jan 11, 2010
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I've been prototyping some kitchen knives that I use in my own kitchen to see how I like 'em. Below is an example. Reasonably high layer count 1095/15N20. I've been doing the etching with Ferric Chloride. I've tried bathing in bleach after - and boiling in water. I hit the high points with either a fine synthetic scrub or "Micro Mesh" to brighten the 15N20.

When I cut an apple some of the oxide on the 1095 discolors the apple. Or when I prep a large meal and some rust starts on the blade - my kitchen response is to scrub with a Scotch scrub sponge. As you can see that removes the black oxides. . . . which I don't really want coming off on my food anyway.

Is there any food-safe way to make the black oxides permanent?

Not a show-stopper - just a "wouldn't it be nice."

Thanks - Michael Kemp

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I finish my damascus etch process by setting the oxides- boiling in water for 15 min. with a little baking soda. Taking it out of the water, I let it air dry, wipe it down with paper towel, then warm it back up over the electric hot plate I use for my boiling rig. I evenly heat the blade until it's uncomfortably hot to the touch, and wipe it down well with peanut oil. Then I might warm it and oil it again. After rubbing the peanut oil off hard, I use a flat hard micarta scrap as a backer with 1500 grit paper to shine the highs. When the contrast is what I want, I warm and oil the blade again.

A deep etch is your friend as far as good contrast, and keeping it that way. Part of the maintenance for a pattern welded kitchen knife should be never to let it rust. Scotchbrite is too harsh for them, I use non-abrasive scotchbrite sponges for damascus in the kitchen.

I find that if you want bold definition in your steel, a lower layer count helps...

Here's an example of what I consider to be an OK level of definition in a PW chef. Peanut oil on the oxides, after boiling.

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It loses some definition over time, but more because the high layers patinate, rather than the low layers losing darkness. To fix that, it can just be shined up with 1500 on the highs now and then. If you're interested I could take a pic of how one of these looks after a couple years of patination.
 
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that about nails it
your going ot get some ware of the contrast cause of patina (darkning the brites)and acids etching out the dark parts i waxed my last blade and it works well for a while but you woudl need to wax often. i kind of gave up on it an just call it life of the blade. if truely worried you woudl need to make the knife a take down so it coudl be reetched whenever it needed to be

i can only hope that some SS damascuse mixes make it to market that have all high grade knife steel in them
some mixes i woudl love to try are XHP/PD1 or cpm154/3v or S110v/M4
 
If you really are in this for the long haul, it is completely worthwhile to set yourself up with a hot-bluing process.
It's the exact same process used to hot-blue your guns.
It's a one-time expense - basically to get the right type tanks - and after that you only need to replenish a five gallon bucket of salts every 3-4 years.
Longer, if you don't make that much Damascus.
Plus, you can hot-blue all your fittings, as well!!
I got my set-up over a dozen years ago, and I have never regretted it for one second.










 
Ya need a much deeper etch and stop using a "Scotch scrub sponge". Just wipe the blade off after rinsing and it'll not rust.
 
Thanks everyone for the feedback!

Salem - I will follow your procedure on my current project.

Karl - my current indoor shop space is miniscule - if/when I build that dream shop hot bluing will be on my list.
 
I dont know that I would hot blue a blade that would be used extensively in the kitchen. I dont know if the blueing is food safe.
 
I don't have a hot bluing setup - but I had mused about cold bluing (Brownells Super Blue).

I've got a D2 blade I made years ago and did a FeCl3 etch followed by Super Blue and it holds up fine. If I get wrapped up in a big meal and leave it wet on the counter only the sharpened edge starts to rust. Yah yah - D2 is *almost* stainless. And yah - if I'm doing something like a big BBQ or Thanksgiving Dinner I get distracted.

But as I'm looking at making some blades for "foodies" - selenium dioxide (cold bluing) is spooky sounding. For myself I'm happy believing that any residual selenium is infinitesimal and benign - but I'll try Salem's route first and see how I like it.

Thanks for all the feedback!

Michael
 
I haven't etched as much Carbon Damascus as the other makers that have shared with you but my process, especially with Carbon steel knives that are used for food prep, is to etch with apple vinegar. Some times I leave it over night, when it gets to how I want it I dump baking soda on it to stop the etch and rinse well under hot water. I shine up the high points with 1000-2000 grit backed with a flat block.

Works great. For stainless steel Damascus, Usually Devin Thomas, I use Ferric Chloride and then the baking soda and wash repeatedly and do the same of the high lights.

So Give the Apple vinegar a try and see if it brings out the pattern in your Damascus they way you want?
 
Laurence - thanks! I'll add that to my list of things to try. I'd played with vinegar - but not overnight.
 
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