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Username Post: Rust or patina?        (Topic#922269)
Journeyman KnifeNut!
04-26-12 19:13.16 - Post#2465538    

This is my Sakai Yusuke 240 guyto made from white #2 steel. It is the extra thin version, 1.3mm across the spine. Still experimenting with bevel angle, the edge has a slight burr a few places.

Anyway... This is my first carbon steel knife. So far it has been a lot less reactive than I had feared. The edge started to take on a blue-ish patina quite early but the rest of the knife showed no signs of coloration for a long time. Absolutely no reaction (color or smell) that tranferred to the food. Recently though, after a session of cutting maybe 40 garlic cloves, a lot of chilliesand a few onions it showed some orange/brown color. I did wipe it down and wash it several times during the session (I am a home cook so my speed is horrible compared to most of you guys...).

Is this rust or is it patina?


Edited by Dieter01 on 04-26-12 19:15.01. Reason for edit: No reason given.

Master Member KnifeNut!
04-26-12 19:59.26 - Post#2465540    

    In response to Dieter01

I just got a Sakai Yusuki white #2 suji a few weeks ago. This is my first carbon knife too, so I'm not an authority. Anyway, mine stayed perfectly shiny for the first several uses but then started to take a patina, mostly down toward the edge. I asked Keiichi and he says these come with a lacquer (or similar) coating that will wear off.

From your photo it looks like the coating is coming off in strips, hence the sharp edges between the shiny area and the yellowish area. I think most of what I see there is patina, but if it were my knife I'd wonder if maybe the coating is lifting up a little before peeling away completely and trapping water or food juices under the coating. If that seemed like a possibility I'd probably try to remove the coating, although I'm not sure what to do that with, maybe someone else will have a suggestion.

Cutting cooked meat seems to turn these a pretty blue, FYI.

How are you liking it otherwise? I got the 270 W#2 suji and a 240 stainless gyuto and could not be more pleased.

Edited by -dg on 04-26-12 19:59.44. Reason for edit: No reason given.
Member KnifeNut!
04-26-12 21:14.16 - Post#2465543    

    In response to -dg

Acetone or some other solvent is the best option IMO
Journeyman KnifeNut!
04-26-12 22:48.31 - Post#2465549    

    In response to Dieter01

Any carbon blade with a orange/brown color to it is more than likely rust rather than patina and should be removed. Many household cleaners will do the job very easily though.
Journeyman KnifeNut!
04-27-12 01:16.28 - Post#2465599    

    In response to Dieter01

I have a Sakai Yusuke and there was a very heavy coat of lacquer on it. I just used mine for a while and eventually it all wore off. It could be rust on yours but I am not sure. I'd try and remove the lacquer anyway and see how the blade reacts then. I think a plastic dish scrubber might be enough to remove the lacuqer, or you could just keep using the knife and see if it wears away
Master Member KnifeNut!
04-27-12 02:42.30 - Post#2465650    

    In response to stevenStefano

Flitz it! Then wash and dry well.
Pensacola Tiger
Master Member KnifeNut!
04-27-12 06:26.55 - Post#2465722    

    In response to Dieter01

Worst case is light surface rust, although it may just be discolored lacquer. It's not patina. Either way, you need to do some maintenance. Use acetone to remove all the lacquer from the blade, then an abrasive cleaner like Bar Keepers Friend to remove the brownish stain if it is still there. The knife shows a vertical scratch pattern from the belt used to finish it, so try to keep your polishing strokes top to bottom to avoid longitudinal scratches.

Master Member KnifeNut!
04-27-12 18:28.10 - Post#2465898    

    In response to Pensacola Tiger

That is the lacquer coming off and exposing the carbon steel to the elements.

I would use some barkeeper's friend to get all the lacquer off, I never trust that that stuff is really food grade.

Bad news is your knife is about to get more reactive. The good news is, it's still the same knife.
Eamon Burke

Burke Cutlery Services

Finish Sharpening on CKTG

Michiel Vanhoudt
Master Member KnifeNut!
04-28-12 04:13.41 - Post#2465980    

    In response to BurkeCutlery

I agree with Eamon and would remove the lacquer. Not too fond of it myself.

I kind of like the effect though. Looks like a city skyline

MIKE #506

My Blog


Journeyman KnifeNut!
04-29-12 05:12.29 - Post#2466289    

    In response to Michiel Vanhoudt

I didn't have that barkeeper stuff or acetone so I tried with a wine cork and some CrO2 paste. It was a bit of work and only some of the lacquer wore off. Here is a picture though, you can see the areas with / without lacquer quite clearly.

As for the knife itself - I am extremely pleased. F&F is very good. It gets sharp, definitely sharper than my CarboNext. I am a home cook but with this knife I feel like a pro when handling the knife, its so light and nimble. It is definitely flexible though so its not for everything, I would not buy this as my one and only guyto.



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