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 Post subject: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 2:49 pm 

Joined: Sun Jul 29, 2012 1:36 pm
Posts: 434
Location: NY, NY; New Haven, CT
I'm very nervous about the colors on my Kono Fujiyama. Despite taking good care of my knife, I get a surprising amount of orange coloration. Sometimes, it seems to look a bit speckled. It has never changed texture to the touch, but I worry that it is too close to actual rust formation to ignore. What is worse is that it seems to deepen in color sometimes (or show up) between uses. I know I am putting the knife away dry, and it seems odd to me that rust would be forming this time of year because it is not very humid. I should be clear that these issues NEVER show up on the Blue#2 core, despite it being very exposed—they are always limited to the soft iron cladding.

I don't like that I have to remove the patina every few weeks, etc., and I wonder if I should just let it be, or if I am doing something wrong. I'd like to hear from others who use Kono Fujiyamas in particular, as I'm sure they are dealing with virtually identical iron.

I'm sending the knife to Steve so that he has a chance to play with it, so I won't be able to take pictures or experiment immediately, and I'll be asking Steve for his first-hand feedback as well. However, I'd love to see others' pictures of "safe" orange patinas if they have them, especially people with Kono Fujiyamas.

I admit that I do not "wipe" the blade between every ingredient or cut, and I often cut one ingredient, set the knife down or aside to scoop the ingredient out of the way, and then attack another ingredient without necessarily wiping the blade down. However, the blade never sits for more than two minutes between cuts without being washed and wiped dry—in other words, it often gets rinsed and wiped between every few ingredients as I turn to the stove or to the sink rinse something off or clean my hands. Like I said, I never notice rust formation or color issues while cooking or immediately after when putting the knife away...I only seem to notice it when inspecting the knife for the next cooking session or sharpening/stropping, etc.

Much of this comes from my lack of knowledge about patinas, so please help. However, because the issue is closely related to the Kono iron cladding specifically, I'd appreciate people limiting themselves to discussions of claddings and not assuming I don't understand carbon maintenance in general just because I don't wipe between every cut. My assumption has always been that, as a home cook, I ought to be able to cut a few peppers and some garlic in the course of 2-4 minutes and not have to wipe the blade down continuously—we're not talking 15 minute sessions peeling and cutting #10 of onions without wiping or anything like that.

Thanks in advance for your thoughts and images!



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Ownership experience: Konosuke, Masamoto, Tojiro, Wusthof, Henckels, etc.
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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 3:43 pm 
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Joined: Thu Apr 26, 2012 5:13 pm
Posts: 2957
Location: CT
I thinned a few of Aaron Gibson's Kono's and they got the orange patina to the cladding pretty quickly. It's probably the metal they use for the cladding that is reactive. I think it was baking soda that was recommended to help with patina's a while back? Use a slurry of it on a cork?


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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 3:48 pm 

Joined: Sun Jul 29, 2012 1:36 pm
Posts: 434
Location: NY, NY; New Haven, CT
Thanks for the comments, Tim. I thought the baking soda was used to clean off a patina. Can it be used as a mild way of forcing a patina with a cork?



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Ownership experience: Konosuke, Masamoto, Tojiro, Wusthof, Henckels, etc.
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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 3:50 pm 

Joined: Sat Nov 08, 2014 11:27 pm
Posts: 126
I don't have one, so cant help ya in your specific case necessarily. Different steels patina and react very differently, so that can account for the difference between the core and cladding. My moritaka tends to get "orange/brown" patina. Been very paranoid about it. But it never really changes in the big picture after many times of trying to observe it after it first forms (i force it, and it always has blues and orange/browns). It changes a lot in light differences, so hopefully you are observing this change under equal lighting. So after awhile, I stopped worrying about ... it didnt discolor an onion, no pitting, etc.

If you are noticing this change well after the fact, im doubting its from any wiping practices. Some knives, people have had them "rust just looking at them" so although unlikely, it could be rusting in storage

I could be wrong, but after years its not changed the knife. interested to hear others observations. I cant see ive been managing rusty spots well all these years, but stranger things have happened.

Steve Im sure will be a help here, and you can perform experiments once you get it back too if you want.

edit: yes baking soda is to remove not develop patina


Last edited by Arlius on Mon Dec 15, 2014 3:53 pm, edited 1 time in total.

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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 3:50 pm 
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Joined: Tue Feb 05, 2013 6:00 pm
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Joe, I recently noticed some orange-ish areas (patina) on my Ikeda AS 250 Gyuto, which has iron cladding as well. It made me a bit nervous, so I lightly scrubbed those areas to remove most of it. I've been using the Ikeda mostly for slicing proteins, but started using it for more general prep as well. My blade cleaning/wiping routine is similar to yours. I'll let the knife sit while I grab something from the fridge to cut, but I rinse/wipe it down pretty often.

I get a nice blue patina when slicing proteins, but the patina fades over time. I've considered a hot vinegar forced patina, but I do like to see the subtle Damascus lines on the cladding. A full-on grey patina might cover that up. I'll guess I just need to try it and see what results.


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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 4:52 pm 
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Joined: Thu Apr 26, 2012 5:13 pm
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Location: CT
The baking soda removes the patina and supposedly helps make the steel less reactive over time.


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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 5:25 pm 
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Joined: Thu Aug 14, 2014 9:05 pm
Posts: 268
A while back I chipped my Kato and sent it in to Ken to fix. I use, wipe, dry my knife the same as you. I had some brown-orange colors on it and thought it was just part of the patina but Ken said it was rust. Since then I've been very cautious about any brown-orange patina and generally my philosophy is to remove it after it begins to form. I use BKF because I had it for pots and pans. It works well. And I find that after using it, the reactivity of the cladding becomes muted. I'm considering other more gentle methods as well, particularly Chip's Korin cleaning cloth + camelia oil routine.

BTW I had a really surprising turn of events using the BKF on my W#1 Fujiyama for the first time. (The Fujiyama cladding seems to be much less reactive than the Kato cladding and it took a while before I decided to remove the "patina" when it started to turn a little brown.) The BKF took the edge off the knife as well. After cleaning it, I felt the edge - just because if I have a knife in my hand I feel obligated to see how sharp it is - and it felt like the toothiness was gone. I then went to cut a paper towel and it could not cut the paper towel. I had just used it to prepare a meal and it was sharp. I was surprised that the BKF had dulled the edge that much. I'm not sure if it is just the W#1 Fujiyama. But I will probably try the Korin cleaning cloth routine as a more gentle way to clean the knife.


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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 5:32 pm 

Joined: Sun Dec 30, 2012 11:01 pm
Posts: 500
Location: ATL
I get a slight orange spot or two on my Kono B2 Fuji cladding at times when I'm using it, especially if cutting onions. My experience is very similar to yours Joe, but it has never gotten to where it was an issue and doesn't happen every time. Like Taz mentioned I use a little bit of baking soda on a moistened piece of potato and the slurry takes it right off. I do this after every couple of uses, takes 2-3 minutes. I've not seen any develop while sitting in the drawer, my experience has been strictly during food contact and never anything that caused concern while using it.


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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 5:48 pm 

Joined: Sun Jul 29, 2012 1:36 pm
Posts: 434
Location: NY, NY; New Haven, CT
I want to thank you guys for your responses so far—please keep them coming! I find this all very reassuring. I was becoming a bit concerned that I was doing something wrong, but this just speaks to the fact that I should either wipe down more often or just get comfortable with the fact that the knife will need to be striped every couple of weeks. I think the most disturbing thing was thinking that I was somehow inept when it came to the cladding on this knife, but knowing others have faced similar issues makes me feel a lot better.

I will say that my perception that it builds after use could be off—I cook at night and the kitchen is not the brightest, so it is possible I only notice the colorations later when inspecting the light in brighter daylight, etc.

Josh: I am often surprised at the power of BKF and have been wondering about alternatives myself. Furthermore, people call it "non-abrasive," but it does remove steel, in the sense that ["dead"] oxidized metal is REMOVED by the product, not somehow chemically altered to restore it back to non-oxidized metal. For this reason, I'd like to use it less often, even though we're talking about microns here, so perhaps I'll try baking soda since it is alkaline and may mildly force a protective patina when cleaning a little bit better than BKF (even though it will similarly remove the corroded steel).

I do have a related question as follow-up. Is it really worth wiping down the blade with a dry towel between cuts? I'm a little baffled at how wiping – not washing/rinsing, but just (merely) wiping – a blade after cutting onions for example would really benefit the knife; furthermore, I know some people use two towels (a wet and a dry) for precisely this reason with some ingredients but not others. It seems that, with only using a dry towel, there would be plenty of acidic residue on the knife and – moreover – that it would be a thinner layer more prone to combining with oxygen to oxidize. I hope I'm wrong in this respect, but it would be nice if someone with experience chimed in. I'd be happy to start wiping the blade with a paper towel or something more often if this actually helped, but the downside is I would probably rinse the knife less during the process of cooking, so I'd only do it if it actually prevented oxidation nearly as well as rinsing during the coarse of regular prep.



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~Joe
Ownership experience: Konosuke, Masamoto, Tojiro, Wusthof, Henckels, etc.
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 Post subject: Re: Rust on Kono Fujiyama?
PostPosted: Mon Dec 15, 2014 6:34 pm 

Joined: Sat Mar 01, 2014 7:15 am
Posts: 1435
Location: Raleigh, NC
I use both a wet and dry towel at all times when using any carbon knife. It's become a matter of habit. There's no kill like overkill and the process takes little additional time.

Regarding the patina, if you are cleaning it frequently to prevent any spreading, I probably wouldn't worry much so long as you aren't getting residue in the food or when you wipe.


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