tell me about Japanese " blue steel"?

M

martin j

Joined
May 16, 2001
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Hello- who knows about Japanese blue steel - is it "carbon" or "stainless" steel, what is comparable to it in American steels?

If there is good link with information, I would be most apprciative.


Also I am looking at Dojo's blue steel kitchen knives here-
http://www.bladegallery.com/knives/type.asp?code=qkitchen&display=Knives+for+Chefs

- Why are these knives much cheaper ( in pricing ) then other production kitchen knives at bladegallery?
Also they are much cheaper then VG-10 kitchen knive by Fallkniven & Almar with Rc62 blades.
The Dojo's are 'good deal" or there is something not evident here?

Thank you,
Martin
 
This is Hitachi Blue Steel. A very high quality, high carbon, non-stainless steel. It is often hardened to 64 RC. It is used in Japanese cutlery and tools.

PS. These knives do look like a good deal. Note that the edge will rust so you need to clean the blades and wipe them dry. I think they would be worth a try.
 
Yup...what Jeff Clark said...

To put two exclamation marks behind his statement:
I find that blue steel takes an extremely good edge, very easily and holds it, too. Personally, I like the white paper steel even better for the same reasons but the blue steel is not far off. White paper steel is essentially a very pure high carbon steel with practically no added elements which improve performance, but without any "impurites" (degrading elements) either. The blue steel is based on the same but has added mainly tungsten and vanadium to improve toughness but more importantly to make tempering easier (white paper steel has a very small tempering window). On the down side: It rusts really easily. Wiping the blade down with oil (mineral oil) after every use is a MUST or the edge will corrode (not to the point where the blade is damaged beyond repair, but were a trip to the stone is necessary).

Last but not least. Since the japanese kitchen knives are highly hardened and the steels are not as tough as you may be used to, they can be sharpened only on japanese waterstones. I tried to sharpen a blue steel kitchen knife on the sharpmaker once and that was not a good idea. The whites with very light pressure are ok, but the grays will destroy the edge. And that's a shame since japaneses kitchen knives are usually hand sharpened on waterstones and come with a beautiful edge.

No there is no catch with the dojo knifes, they will perform beautifully. But they are different from European style kitchen knives and are not everybodies cup of tea. I personally prefer the Hon Kasumi series, which I think is the steal of the century, but since they are single bevel (traditional style) they require even more getting used to.
 
I have to agree, just keep them dry and cleaned. I use Flitz Stainless Steal and Chrome Cleaner, although I would think any chrome cleaner would work

SFC
 
There are three types of Hitachi Blue Steel.

Hitachi Blue No.1: C 1.2% - 1.4%, Si .10% - .20%, Mn .20% - .30%, P </= .025%, S </= .004%, Cr .30% - .50%, W 1.5% - 2.0%

Hitachi blue No.2: C 1.0% - 1.2%, Si .10% - .20%, Mn .20% - .30%, P </= .025%, S </= .004%, Cr .20% - .50%, W 1.0% - 1.5%

Hitachi Blue Super: C 1.4% - 1.5%, Si .10% - .20%, Mn .20% - .30%, P </= .025%, S </= .004%, Cr .30% - .50%, W 2.0% - 2.5%, Mo .30% - .50%, V .30% - .50%

The Spyderco steel chart has Super Blue also containing some nitrogen, but this is incorrect. The above specifications came directly from Hitachi Metals.
 
I have a san mai kitchen knife with a blue steel core and stainless sides from Murray Carter. It is one of the sharpest knives I own. The edge has aquired a blue patina that comes off when I sharpen it. Great knife and great steel.
 
WOW thank you for reply from everyone, very good information :cool:

I understand it must be wiped and dry - it is similar to carbons steels like 10xx series, 0-1 and similar I assume? If this is so then it is easy enough to provide maintenance.

Thank you for your wisdom -
Martin
 
HoB said:
Last but not least. Since the japanese kitchen knives are highly hardened and the steels are not as tough as you may be used to, they can be sharpened only on japanese waterstones. I tried to sharpen a blue steel kitchen knife on the sharpmaker once and that was not a good idea. The whites with very light pressure are ok, but the grays will destroy the edge. And that's a shame since japaneses kitchen knives are usually hand sharpened on waterstones and come with a beautiful edge.
Click to expand...

thank you for this information, from data by Kieth Montgomery it looks like Blue Steel is like higher carbon version of 0-1 steel yes? By " not as tough" is it similir to D-2 at 62Rc or it is even more fragile? Thank you-
Martin
 
Unfortunately, I don't have a blade in D2...yet. But from what Cliff Stamp for example says about D2 and the fact that even larger hard-use fixed blades like the bog dog use D2 in 62 Rc, I think D2 is far from brittle. It may not have the toughness of A2 or 1052 but especially in comparison to the stainless steels it is supposed to be quite a tough steel.
In my experience blue steel (at least the way it is used in the japanese kitchen knives) is quite brittle (which is why the blade is laminated with soft iron). I guess I would compare it more to the steel used in a traditional straight razor.

If you are used to other non stainless steels you should have no problem with corrosion...just don't leave it in the wet sink for a few hours, like one of my housemates :( . But even then, after a trip to the stone it was ok again, just a little discolored.
 
I have the Dojo Blue Steel small slicer. It is a fabulous culinary knife and I would recommend that you buy it first. I have yet to find anything it cannot do well as far as my food preparation is concerned. Yours may vary, so you could add to your collection as needed.

The main reason for their lower cost is that they don't have bolsters, so make sure you rinse that area well of food particles that become lodged. Use a toothbrush if running water doesn't work. It's not much effort and they're worth it.

Also, the tang isn't the full width of the handle. The underside of the handle is all wood - rounded and comfortable.

The steel does develop a patina. That doesn't bother me, but you could easily remove it with Flitz metal cleaner. I have yet to sharpen this knife. I will try my diamond hone first. If that doesn't work, I'll try the Japanese waterstones suggested.

I've also tried the Hon Kasumi small slicer. The blade was noticeably thinner and not quite as good for heavier slicing; and that beautiful folded-steel pattern looked like hell after a few scratches, which you will get on your kitchen knives!
 
Swamp Rat's D2 line is very tough, for a D2 steel blade. But the flexibility and impact toughness is still significantly below the carbon steel line. Is it tougher than stainless, in general yes as stainless steels in general are fairly brittle. But that is like saying you are slimmer than Butterbean, its a standard that's easy to beat. I have used extensively a Safari Skinner in D2 and can say that its easily one of the tougher D2 blades I have seen, and its even tougher than some of the A2 blades I have seen (Reeves for example), which shows you the difference that heat treating can make. Swamp Rat does however not overhype the blades and do take care to note that the carbon line is the one that should be used for the heavier, chopping, prying and in general more "tactical" blades.

-Cliff
 
I'll try to simplify it for you. Traditional Japanese kitchen knives, at least the better ones, are made from either shiroko or aoko. Shiroko is called white steel because it comes from the mill wrapped in white paper. Aoko is called blue because it arrives wrapped in blue paper. Sometimes it is called Aogami or blue paper steel. Both of these steels are high carbon steels that can be and are hardened quite a lot to allow the application of acute bevel angles (usually single bevel at that.) Typical hardness levels in finished knives are RC 63-64.

The blue variety (someone already pointed out that there are different grades) basically has some added elements like chromium and manganese to give it better abrasion resistance. So the blue steel knives tend to hold an edge a little better than the white and last longer over their lifetime. Blue steel is, however, harder to maintain and is generally recommended only for cooks who are serious about knife maintenance.

The aoko or blue steel also tends to discolor more slowly than white steel although it will discolor just fine.


There are a couple of choices on the construction of the knife and it's probably easier for me to direct you to an article of mine at http://www.knifeoutlet.com/traditional.htm. It will tell you more about traditional Japanese cutlery in general. Good cooking.
 
DRM said:
I've also tried the Hon Kasumi small slicer. The blade was noticeably thinner and not quite as good for heavier slicing; and that beautiful folded-steel pattern looked like hell after a few scratches, which you will get on your kitchen knives!
Click to expand...

Mmmh, I have never seen a small slicer in the Hon Kasumi line, nor have I seen one with a damascus Jigane. I am pretty sure you are thinking of a different line? Hon Katsumi is a brand of kitchen knives. The direct translation of the marking on the blades of this brand is actually simply "Japanese Kitchen Knife" (I found somebody, who speaks Japanese to translate it for me :) ). Hon Kasumi also refers to a welding type and is sometimes misused as term for a pattern welded Jigane (Damascus) which would correctly be Suminagashi (flowing ink, derived from Japanese paper marbling). I haven't been able to figure out exactly what Hon Kasumi refers to, but it seem to refer to the Hagane forge-welded to a single slab of wrought iron, while San Mai designates the Hagane being enclosed by two slabs of Jigane. Please, if somebody knows better please correct me. Unfortunately, these terms are not exactly ones you could just look up in a Japanese dictionary.
 
Kasumi is a forge welding of a hard hagane and soft jigane (usually iron.) There are simply a layer of each forge welded together. The inside of the blade will be the hagane and the outside the jigane. The "hon" in front of kasumi seems to refer to kasumi style knives of higher quality. Of course, I've seen some pretty awful traditional Japanese knives called honkasumi.

The purpose of kasumi construction is to make the hagane thinner so that it is easier to sharpen and less expensive. Making a knife from solid hagane and then differentially tempering it is called honyaki and is difficult and expensive. The blade comes from the forge bent and straightening it causes some failures and these failures require the knife maker to start over. Kasumi construction is easier and less expensive.

San Mai, as far as I know, is not a Japanese term and refers to nothing in the Japanese knife making literature. I think it is something that has been popularized by Cold Steel. I've heard the term warikomi referring to knives with a hagane surrounded on both sides and the top by a stainless jigane. The better ones, again, have been called honwarikomi although I have seen this term used on relatively inexpensive knives.

I've also seen inconsistencies in knife terminology among Japanese makers. I'm not sure the terms are as rigid as we'd like them to be. As an example usuba normally refers to a single bevel vegetable knife and nakiri to a double bevel one. But, I've seen double bevel ones called usuba as well. It's pretty confusing.
 
Excellent information, KO, thanks!

Flipping a few catalogues I also found the brand that DRM was talking about: Kasumi (without the "Hon"). Double bevel, suminagashi jigane surrounding VG-10 hagane (warikomi style). Looks very nice (and rust proof), but virtually identical to the Shun series which is a few bucks cheaper....sold by knifeoutlet by the way :) .
Speaking of which: I have trouble to access some pages on your webpage, KO, for example the Shun page it loads but it doesn't contain anything but the sidebar. Is that my old browser or is there a trick?
 
HoB said:
Excellent information, KO, thanks!

Flipping a few catalogues I also found the brand that DRM was talking about: Kasumi (without the "Hon"). Double bevel, suminagashi jigane surrounding VG-10 hagane (warikomi style). Looks very nice (and rust proof), but virtually identical to the Shun series which is a few bucks cheaper....sold by knifeoutlet by the way :) .
Speaking of which: I have trouble to access some pages on your webpage, KO, for example the Shun page it loads but it doesn't contain anything but the sidebar. Is that my old browser or is there a trick?
Click to expand...

The Kasumi brand knives are distributed by the US distributor for Global Knives. They are comparable to the Shun. The blades are the same but the handles are different. Nice knives. Our web site, in order to be competitive for attention by the search engines, has some fancy programming that turns database records into html pages on the fly. If your browser is old enough, it won't know how to interpret it. Perhaps it is time to get a newer version of your browser. You may need it for other higher technology web sites as well. Glad I could help with the Japanese knife terminology. I do this for a living and I'm still learning more about Japanese kitchen cutlery every day. You can read some of my Japanese gyuto reviews at http://www.foodieforums.com. Good cooking.
 
More excellent information, thank you Knife Outlet for your link, very informative, and everyone else for our experiences and 'detective' work on terms.
Martin
 
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