My favorite color is BLUE!.............A patina thread.

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Mrchainsaw

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I’m new to knives. How do you control the color of your patina? For example, what would patina look like even on carbon so dark such as this:
77C4C5FC-19BB-4BAE-88F2-5F31D89FAA7F.jpeg
 

btbyrd

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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.
 

btbyrd

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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.

0A5372D2-08F0-447D-A549-91346138857C.jpeg

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.
 

jsph

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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. ...?)
 
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btbyrd

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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.
 

jsph

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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.
 
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