I was wanting try forcing a patina on a carbon steel knife blade using a grapefruit. The least expensive way for me to try it was to buy an Opinel carbon steel knife, and a grapefruit.

I shaved the skin off the grapefruit, cleaned the oil off of the blade using acetone and pressed it through the widest part of the grapefruit. I left it in that spot for an hour and a half.

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When I took it out the acid had etched more on the ends of the blade and less in the middle. I think the middle of the blade was in the center pulp part of the grapefruit; the ends were more in the juicy part. I pressed the knife back in the grapefruit for another hour so the middle sat farther from the center. That evened it out. I pulled it out after another hour and it had evened it out. To even it out even more I placed a small slice on light spots. I cleaned and dried the blade, sharpened it and oiled it. This is how it turned out.

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If I do it again I’m going to cut the grapefruit in slabs and set them on the blade. The etching didn’t happen very fast, so there would be plenty of time to check the progress and reposition the slabs.


Bill

If you could redo the pics, it says invalid attachment.
I'd like to see how the blade came out for you.
I've done a few blades using aqua Fortis to rust the blade, then after its rusted some place it in boiling water. The rust turns blue and you have rust blued knife. Heres a few I've done, the 4 on the left are rust blued.

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I smeared some hot sauce on my knife blade to make a patina:



Worked well.

After reading forum posts by Randall Knives dealer Chris Stanaback about using pickle juice to force a patina, I've used vinegar on a few of my "user" carbon steel Randalls and have been very pleased with the results.

These were done with Hoppe's Gun Blue, the old bright blue liquid stuff, which is selenious acid, in the glass bottle. It works pretty much instantly. Apply it, wait a few minutes, rinse in cold water and you've got instant patina.

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SWHF #448

Yellow Mustard also does a good job...as does a potato...as does a tomato. Etc.

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C & L

Nice “stag” handle Opi. You do that? Looks cool, like a jigged bone’s grips from the old west.

Yes, reshaped it, hit it with a small torch to flame the wood and then used a soldering iron to do the jigging.

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SWHF #448

This was a base of vinegar with cheap yellow mustard for the design on a Cold Steel Folder. Lots of fun designs to experiment with!

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I can only load one photo at a time for some reason, so...
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Bill

Edit: Anyone know why this has the attachment and the the thumbnail?

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And another.
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Bill

And again.
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Bill

I like the mustard patina, too. I've read that the acid needs air, (aerobic,) to etch the steel. That's why it will etch the steel at the edge of the mustard and not under the mustard.

Bill

An apple will do it too.

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S&W Accumulator

Just about any acidic fruit or vegetable and potatoes will darken a blade . Lemon and lime juice , most citrus . Pickle juice has a lot of vinegar as does hot sauce and the juice pickled peppers is in ... they will all work. Yellow mustard does a great job .
Just use your knife in the kitchen for a while...food prep wiil do the job in short order !
Gary

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Certified Cajun
NRA Member

You are better off using acidic liquid. I have used many juices and pulp type acidics to match patina. Different things cause different degrees of
color. Usually sticking a part in a fruit will not provide even coverage. I have used a lot of tomato paste, put it on and let it dry and sit overnight.
Wipe it off and repeat if not dark enough. I'm sure there are chemicals that would work better if one knew what they were doing.

Cool thread.

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Miss Buddies crsides & fat tom

Pass the Grey Popoun please ��

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Patriots Forever!!

Very nice. I did one on a C V Case muskrat last week boiling vinegar

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Spin The Wheel

Great idea. I have an Opi 10 that is a work in progress. Maybe I will try it on that. I should eat more grapefruit anyway.

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Not in jail.

I guess I'm behind the times . I just put it in my pocket, and within a year or two , it's patina'ed .

I used plain unheated white vinegar to apply a fine, even, gunmetal blue-grey patina to several knives. Just immersed the blades, up to top of the ricasso, for a few hours, then rinsed thoroughly and applied a very light film of Rem-Oil. The patina wore well. No waste of fruit or vegetables.

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Oh well, what the hell.

Dressing out a deer or elk seems to do the trick, too, if that's what you like. Not much of a design...just patina.

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Pack light and cinch tight.