Yes, though I've only used it to prep one small meal at home. But I washed and rinsed it five or six times, including with a blue (nonstick-safe, low abrasive) Scotch Brite dish wand thing and the patina stays put. Wiping it clean leaves nothing behind on the towel.
So full disclosure: It’s a little less murdered out than the original high contrast image suggests. It’s more of a very dark grey. Here’s a comparison pic with some better lighting.
A lot more attractive than the splotchy patina it used to have, and now I can cut onions without them going black and sulphur-y. Happy with the results, even though I’m not usually one for forced patinas.
still... that's ridiculous. wow. inspired me to push a little carbon paring knife into an apple and wait a few hours, but all the dark stayed with the apple. i'm assuming you dissolved some store-bought malic acid powder in water and just let this guy soak in a bottle for however long...?
b. was there much of a reaction with the brass ~bolster?
c. how much did it dull the edge?
(d. i had heard the kramer 52100 wasn't super-reactive, to be making so much of a mess with onions, etc. ...?)
The idea was sparked by the blue patina I noticed on some of my Blue 2 knives after I sliced a bunch of granny smiths to make pies with. I was hoping a malic acid bath would smurf out the blade, but it darkened deeply instead. Of course, this was a much more acidic solution. I happened to have a sack of malic acid on hand so I dissolved some into a liter of water on the stovetop. I didn't really measure, but I used quite a bit. It was definitely more acidic than mustard or coffee -- well into the stronger vinegar range. Once the crystals were dissolved, I placed the hot solution (maybe 160F) into a container along with the knife so that it covered everything up to the very tip of the bolster.
The bolster did not react at all, which surprised me. I checked the color of the blade after about 5 minutes and did an initial wash to see if the patina was staying put. It needed more time, so I put it back -- repeating this process every 5 or so minutes for 20 minutes. By that time I was satisfied with the color and evenness of the patina. The edge got less sharp, but only required a few strokes across a fine stone to bring it back. The Kramer 52100 isn't very reactive, but I had recently stripped all the patina back because it was splotchy and dirty looking, and the stripping made the whole blade as reactive as it was when I first got it. Again, this wasn't very reactive but I'm sensitive to the onion/steel reaction and wanted to go ahead and take care of that.
got it. thanks so much for the excellent level of detail on that. interesting about the bolster, too, though i shouldn't fool myself into thinking i understand brass any better than i understand steel. wouldn't have thought granny smiths would create a blue patina, so i'll have to try that soon. i've been playing around with a cheap carbon paring knife whenever a thought occurs.