Are patena's good or bad?

Joined May 13, 2017
just got a new knife the gesshin ginga white #2 gyuto and it seems to be forming a patena on the top half of the knife. it is a bright reddish color and i am worried that it is a bad thing. i heard patena's are supposed to be good and kept but i am also reading around where people are talking about red patena's and black patena's and how you want it black not red. pretty confused right now. 

my other knife also has a patena but only at the edge and it's really dark red until i sharpen it then it comes off it is blue steel but the inside is carbon i believe. 

any help? should i leave it alone and continue using or should i remove it? if so what is the best way to remove it without damaging the knife. i hear baking soda and scrubbing works if it's light but seen someone mention steel wool with a finer grain or sand paper to scrub it and that seems really damaging for the knives. i am mostly concerned about the safety of the food not the looks of the knife along with the knife keep of course. tried wiping the knife after cutting acidic food constantly but there is only so much i can do when it gets really busy and just need to let it be. 
Joined Nov 15, 2012
I didn't know the Ginga was monosteel.  I'm not sure if this red patina is rust or not.  Meat gives a blue color, as does some acidic fruits like mango.  Lemon peel/lemon oil gives a nice sheen to an existing patina, just wipe it on then rinse it off.

Keep a dry towel and a wet towel at your station so you can occasionally rinse and dry as you work.

Here's how to force a black patina:

Here's even more than you'd care to know about patinas and what they can look like:!-A-patina-thread?highlight=red+patina

Someone here did some great artwork using mustard, can't find it right now.  Basically you just establish an overall patina, then daub on mustard as if you where, making a textured oil painting.
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Joined Aug 6, 2015
Hard to say without a photo

Yup baking soda and scrub could work
Fine grits of sandpaper like 800-1000+ would also probably take it off just be careful and stay away from the edge. You will see these scratches. Same with finer steel wool
There are also rust erasers, fine grit, for maybe 10-15 bucks online
If it's a really light spot, sometimes, I'll just wipe a bit of medium-fine grit stone slurry from sharpening onto a paper towel or piece of cork and rub that on the spot, then wash and wipe off
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Joined Nov 15, 2012
Oh yeh, the rust removal, along with foody's recs, there is Flitz, Bar Keepers Friend and products like Bon-Ami.  Paper towel is fine or, as the pros seem to prefer, a halved spud (or daikon radish like the Japanese) as your "applicator."
Joined Feb 16, 2013
If you left the knife wet for a long time, even say 5 minutes, there's a chance some of it is actual rust. Although that's not a good thing, no need to panic, as you alluded to and Rick and Foody said, it's really easy to get surface rust of a knife, just don't let it pit. 

When I first got a Masamoto KS one night I left it wet for like 10-15+ minutes when the phone rang in the middle of cooking iirc, and it got some rust. I freaked out lol, and made a thread like this one but in much more of a panic. Basically it came out no problem, a baking soda slurry and a sponge and had to follow it with a little BKF for one tough spot, but I owned the knife and used it constantly, well over a year after that and never had anything other than an awesome patina. I really regret trading that knife. 

White steel tends to be more reactive than blue in my experience of both use and researching online. But then again, I own an Ikeda Damascus KS clone in Aogami Super and it's very reactive. 

Bottom line is don't be afraid of high carbon knives, but you have to respect them and maintain them as they should be. If you don't want rust, you have to keep a damp and a dry towel handy all the time and although some people are anti-patina, I'd suggest building a proper patina on the knife, it not only adds a cool look to it, but actually helps protect it against rust. 
Joined Feb 16, 2013
@Dave Kinogie I'm guessing your KS clone was iron-clad? That stuff I've found to be much more reactive than even the low alloy hard carbon steels

It's this one. I'm actually probably looking to sell or trade it soon. Although I love the KS profile and an original Masamoto KS is something of a nostalgic knife for me and this knife is great looking, great performer and fit and finish, but I've slowly become much fonder of smaller knives, 210's and nakiri's. It's also a little too reactive for my liking. IDK though, I don't think this knife is ever being made again though, so I might keep it. 
Joined Mar 8, 2012
I've got an Ashi Chinese cleaver in that same steel- monosteel white #2. The patina shouldn't be red or orange, but that is an easy fix. I like to use Bar Keeper's friend, which is a mild acid that will scrub away any rust you don't want. You should be able to find it at your local supermarket. I just wet the knife, sprinkle on some BKF and rub it in with my fingers. Let sit for a couple of minutes, then rinse off thoroughly. You can also then repeat the treatment with baking soda. The baking soda will tend to neutralize an residual BKF. 

Here's a good video on a workflow with carbon steel:

Going forward, you can just use the knife a bunch and not let it sit around wet. You should end up with a greyish patina with blue and rainbow highlights, but it all depends on what you cut. 

The other option is to force a patina. One way is to use mustard. Clean the knife with rubbing alcohol to remove all traces of any oil. Smear it with mustard all over. Let sit for half an hour. Rinse. I did this at one point with my Ashi. It made some interesting patterns, but nothing that stayed around too long. I find it better just to let the patina develop naturally. 

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