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View Full Version : Iaito..Chrome vs Aluminum\Zinc



Scotoe
10th January 2006, 19:20
Just wondering which is better for the long run..(5-9 years).. i.e. handling, maintenance, durability, flexibility, stability. Any input will be appreciated. This will not be my first. I have a refitted Chen Nami, and now Im looking for something heavier (880g-1100g).

Thanks!

Maro
10th January 2006, 21:00
Nearly all non-Chen Iaito are Chrome plated Aluminium alloys (Zinc/Beryllium etc).

It's not a question of and/or.

Any input from your Sensei. Some styles prefer light Iaito and vice-versa.

Scotoe
10th January 2006, 22:34
thanks for the info. I was looking at Bogubag, and there it says their blades are chrome. Where as at Swordstore and E-bogu they say thay are zinc/aluminum. What is the difference with repect to my first question?

Maro
10th January 2006, 23:01
Usually Beryllium is used in the heavier blades. There are no Chrome blades - it's not structurally strong enough. Chrome Plated is what they mean.

It's totally normal to have a Al/Zn blade. They will all be plated with Chrome as well. It has no bearing on performance either.


Seriously, your Sensei will be able to explain the difference. You shouldn't go off and buy a heavier iaito if you're style doesn't suit it.

:)

Chidokan
11th January 2006, 21:44
buying a heavy sword is missing the point. At your level you need to develop finger and wrist control, which is difficult with a heavy sword. For an extreme example of this try using a plastic saya as a sword, look how easily it moves during the transition from nukitsuke to kiritsuke. Now try the same speed and control of movement with an iaito....

yoj
11th January 2006, 22:17
The chenstuff is a low carbon steel plated blade, , mogito (normal iaito) are plated alloy, the chen stuff is less forgiving of a fluffed cut, and will tend to bend easier.

Hope that helps.

Charles Mahan
12th January 2006, 05:56
Not to mention it they Chen stuff cannot be taken on training trips to Japan, which is not a consideration for everyone, but is for some.

Jawa
13th January 2006, 21:32
First off, check with your instructor. Some styles are specific about blade length, handle length as well as blade dimensions such as sori and kissaki (curvature and the type of point). As has been pointed out, iaitos come as either a Zn based alloy or some sort of steel.

Ahmed

Ken-Hawaii
14th January 2006, 07:45
Ahmed, please list your full name on your posts, per the rules.

On the subject of iaito, there are a lot of opinions, & here's another from a chemical engineer. The two primary types of "true" iaito are made from either a zinc/aluminum or zinc/beryllium alloy. There are advantages to each of these, primarily for density (weight) & balance; & of course neither can be sharpened. It's bloody hard to stick chromium chemically to either of these alloys, so as several iaito manufacturers have explained to me, they "direct anodize" that nice shiny surface, but it's not chrome because it doesn't have any chromium in it. I can figure a couple of ways to actually chrome an Al-Zn surface, but it would take several intermediate metals (nickel & either steel or gold), which would drive the iaito prices even higher than they are now. I stick with Zn-Al primarily because I happen to know that beryllium is one of the most poisonous metals we're likely to encounter; check out www.webmd.com/hw/health_guide_atoz/nord481.asp if you want to get scared.

Other "iaito" can be made from steel, usually 440C so it can be nice & shiny. These blades can be really dangerous! Why, you might ask? Well, any time your blade contacts a solid object (floor, mats or bamboo for tameshigiri, etc.), there is a considerable amount of force transmitted through the metal. Steel, in particular, has a tendency to develop stress-cracks from this type of use, often beneath the habaki, where you don't often look. And the tsuka also gets a lot of stress, which is why you should be checking your mekugi more often than you probably are....

You'll never find a "chrome" blade on a sword because chromium doesn't have enough structural rigidity to be useful. It's simply a nice alloy to make shiny surfaces that rust really fast out here near saltwater. You'd be astonished how many motorcycles are painted on all surfaces out here in Hawaii!

Anyway, if a vendor claims they're selling "chrome iaito," it might be a good idea to steer well away from them. :p

Jawa
14th January 2006, 13:28
Sorry about that, i will know in future.

The only thing i can think of is that they mean it is stainless steel since that has chromium in it. Which is fine for an iaito NOT for any contact whatsoever as the results can be catastrophic with stainless.

The chromium as a coating is nice and shiny until you get a scratch in it. Then its bye bye as corrosion sets in. You can't beat a lick of paint :)

Either zn alloy or the steel is fine for the iaito. It comes down to the manufacturers ability to make a well balanced sword. For instance swordstore.com make great iaitos which are made from zn alloys. Obviously they are designed for no contact use.

Ahmed Hussain

Brian Owens
15th January 2006, 12:28
...I was looking at Bogubag, and there it says their blades are chrome. Where as at Swordstore and E-bogu they say thay are zinc/aluminum.
I have a BoguBag "Dotanuki koshirae" mogitoh (iaito), and it's chrome-plated alloy just like the other major brands use. In fact, most of the suppliers get their parts from the same manufacturers, and are simply assemblers and/or resellers.

If it's true that chrome doesn't stick well to zinc alloys, it could explain one slightly disappointing thing about my iaito: there are a few places where there are "bubbles" on the coating, and one of them on my blade is along the mune about 10 inches from the kissaki...right where I feel it during noto. (Maybe I'll have to take up Muso Shinden Ryu.)

It looks like the blade was heavily sprayed or dipped; not anodized.

tsurutengu
15th January 2006, 15:51
... Other "iaito" can be made from steel, usually 440C so it can be nice & shiny. These blades can be really dangerous! Why, you might ask? Well, any time your blade contacts a solid object (floor, mats or bamboo for tameshigiri, etc.), there is a considerable amount of force transmitted through the metal. Steel, in particular, has a tendency to develop stress-cracks from this type of use, often beneath the habaki, where you don't often look. And the tsuka also gets a lot of stress, which is why you should be checking your mekugi more often than you probably are....
Generally I ignore comments made about 440C because there have been so many debates about its use. However, 440C is just fine for iaito as long as it is not fully hardened. Fully hardened 440C is brittle. Where brittle is often defined as less than a 5% difference between ultimate and yield strengths. A better application for fully hardened 440C would be for scalpels and pocket knives.

Any steel will develop stress cracks with repeated flexing over time (commonly referred to as fatigue) if the stress exceeds the endurance limit for the steel. Generally these cracks occur at discontinuties in the material. This could be a lap or fold in a forged carbon steel blade or at the habaki notch in a 440C blade. However, this may not occur during the usable lifetime of the blade.

If I had to guess (guessing because I haven't looked into the process) I would say the iaito's I have seen were either chrome or bright nickel plated. In any case, most chrome and nickel plating is preceeded by a copper plate.

You'll never find a "chrome" blade on a sword because chromium doesn't have enough structural rigidity to be useful. It's simply a nice alloy to make shiny surfaces that rust really fast out here near saltwater...
Small correction here. Chrome doesn't 'rust' (rust is reserved for iron), the base metal develops corrosion because the chrome is actually a porous coating. Even 'stainless steel' will rust, especially in a salt fog environment. Chemistry was not my favorite endeavor, but if I remember correctly (been well over 40 years ago) Chromium is an element not an alloy.

...You'd be astonished how many motorcycles are painted on all surfaces out here in Hawaii!And a whole lot cheaper.

Jawa
15th January 2006, 19:54
You are right chromium is an element.

One reason why stainless steel blades shouldn't be used for contact is that the chromium can segregate to grain boundaries forming inclusions with carbon in the steel which acts as "failure" points.

Cycling loading (Below endurance limit) can still lead to failure, it all depends.

Brittle is bad, i guess thats why martensitic structures are out :rolleyes:

Not so sure on the beryllium alloy, i thought that was toxic.

Ahmed Hussain

Maro
15th January 2006, 20:48
I'm not sure. I think Pure Beryllium is. I know you have to be careful recovering it - the Aus Navy is fightinh a Lawsuit against sailors who were exposed to it whilst working on Maintenance in Ships.

I have the Dotanuki and it's Al/Be - let's hope it's not!

Brian Owens
15th January 2006, 22:09
...Not so sure on the beryllium alloy, i thought that was toxic.
It can be (but so can many other substances we're exposed to on a daily basis).

Just don't grind your Zn/Be iaito blades into powder and then breath the particles. ;)

Exposure to beryllium dust can lead to a disease called berylliosis.


Some of the most common symptoms of Chronic Beryllium Disease are:

Cough
Shortness of breath
Fatigue
Weight loss
Loss of appetite
Fever
Night sweats

Symptoms of chronic beryllium disease are breathing difficulties, coughing, chest pain, and general weakness. Signs include enlargement of the liver, spleen and right heart, and kidney stones.

The course of chronic beryllium disease varies. Some affected people may have few or no symptoms at all for many years followed by eventual deterioration. Symptoms of Chronic Beryllium Disease may take 10 - 15 years after Beryllium exposure to appear.

Aozora
5th October 2007, 16:18
Sorry to resurface this old thread. I hope it goes to the sword craft section--if not, please feel free to move it there.

My question is what are the issues in using one of the newer stainless steel iaito (mogito) for regular solo practice versus the traditional chrome plated alloy blades?

I ask this because I have had bad experiences with the chrome plated ones--flaking occurs after a period of time. I am told that I have had bad luck with them, or that because being in an area with high humidity might have something to do with it (although many places in Japan are also humid).

I know one issue with the stainless steel is what Charles Mahan-sensei brought up in that you can't bring them to Japan to train. I know firsthand, as they used little magnets all over my alloy blade to make sure there wasn't any steel in it (a hilarious experience).

The thing is, for practicing here in the states, it would seem more sensible to buy a stainless steel sword, as it will last longer without worry of flaking or marring the blade. It seems to me the alloy blades would have the same issues as stainless for incidental contact, ie. breaking/bending, etc.

Also, the guys at Nine Circles say their 430C ss blades are less brittle and more durable than the 440 kind. For the metallurgists out there, how would they compare, especially for iai practice (ie. years of swinging them)?

Strictly speaking, I want to know why, given domestic practice over a number of years, one would choose a zinc/alloy blade over a stainless steel mogito (not the cheap wallhanger variety)?

Ken-Hawaii
5th October 2007, 23:39
Probably the most important factor in deciding which material is used in a blade is what your sensei wants you to use. Zinc/beryllium & zinc/aluminum alloys have in their favor that they can't be sharpened, which is a big plus in a dojo with a bunch of new students. Maeda-Sensei doesn't allow any steel blades (i.e., shinken) in our dojo unless a student holds MJER shodan or above, & we must advise him that we're using one as soon as we arrive. A wise choice, in my mind.

Looking back over last year's discussion, I'm a bit surprised to find that there are still chrome-plated iaito available. Zn/Be & Zn/Al can't be chrome-plated, & there is no way for them to rust or flake, so I'm curious as to what you really have that does flake. As far as marring the blade, unless you're hitting the floor, I don't see how you can do much of any damage to the iaito surface. I know that my Zn/Be blade has been through a lot of years of practice without any noticeable wear & tear. I've replaced a few saya, though.... Early on, Sensei did have us practice nukitsuke by having us swing at a thick telephone book, but I can't think of anything else that my blade has ever contacted (with apologies to our well-nicked dojo floor).

As far as stainless steel versus the above alloys, assuming that you're not performing tameshigiri with your iaito, I don't know why you would want a steel weapon at all. They are prone to rust, require a lot more care, & weigh more, as well. If your style of iaido requires a shinken for practice, then you would be better advised to find a blade based on what was used for many hundreds of years to make Nihonto -- & that does not include stainless steel!

I've checked out a number of S/S blades over the years for applicability in tameshigiri, & have sent every one of them back, including two of them in multiple pieces. The closest I came to keeping one was a blade with folded & forged S/S (I think it was 316, but it's been awhile) with a nickel alloy (not sure which one). A very attractive Damascus-like pattern, & it cut really well, but it was a bit more expensive than I was willing to pay at the time.

From a metallurgy standpoint, just about any metal blade will work for standard iaido practice. You would have to be contacting something for any chance of failure, assuming you keep your blade well-oiled.

Brian Owens
7th October 2007, 14:24
...Zn/Be & Zn/Al can't be chrome-plated....
My zinc/aluminum iaito is definitely coated with something.

Maybe it's not "plated" in the technical sense (maybe it's dipped or something), or maybe it's not chrome (as in real chromium), but there is a shiny, silver coating that looks like chrome.

It has some bubbles in it, and looking at the nakago area allows me to see the underlying metal, so I know that this outer metal doesn't go clear through.

pgsmith
10th October 2007, 22:43
Hi Ken,
A couple of misconceptions that need to be cleared up ... Firstly, all alloy iaito are primarily aluminum and zinc. Some have beryllium added to the alloy, but it is in small amounts only. It supposedly produces a denser and stiffer alloy which more closely resembles the characteristics of steel. It would probably be quite poisonous if you ground your whole blade up to powder and snarfed it, so don't do that! :) Almost all alloy iaito are chrome plated. Since chrome will not stick well to aluminum, the iaito are first copper plated, and then chrome plated. If you ever have the opportunity to file out a large ding in your iaito (yep, I was too close to the wall!) the layers of copper and chrome plating are clearly visible. I've personally seen a few inexpensive iaito begin shedding their plating as they skipped the copper step, and were chrome plated straight to the aluminum alloy.

These are statements I was told by way of conversations with one iaito maker. While it's possible that he was feeding me a line, his explanations seemed to make pretty good sense to me.

Ken-Hawaii
10th October 2007, 23:28
Hey, Paul, good to hear from you. I'm not very surprised to hear that there are many ways to make iaito these days.

I happen to know that my particular iaito is made from zinc & beryllium because I had the chance to tour the manufacturing process while I was in Japan waiting for it to be made to my specifications. I kinda' got the hint when the production manager handed me a respirator before we went onto the shop floor - you don't need a protective mask like that for zinc & aluminum. My Japanese isn't very fluent :D, but the skull-&-crossbones sign is quite international :eek:.

Likewise, my blade isn't plated with copper or chromium, but is rather polished to a very high sheen that has lasted me many, many moons. After several million nukitsuke & noto, I'm fairly certain that I would see at least some sign of wear if the polished surface was plated. I've gone through three saya, with repairs on several of them, but my blade surface is still pristine.

I can see where an iaito vendor might choose to plate his wares, especially if there's not a lot of hand-workmanship involved. But copper isn't known to stick very well to aluminum alloys, although zinc would be okay as a substrate. I have my metallurgy books in front of me trying to determine if there's anything written about copper- or chrome-plating on aluminum-containing alloys, but haven't found anything as yet.

Brian, I'm curious about the bubbles in your blade's coating. Could you post a close-up shot of that area? It might give me some hints on how it's constructed. Dipping is a cheap form of electroplating, by the way, so there's really not much difference. I also have a call in to a friend of mine who manufactures iaito to see if he can shed any light on the process. Most of his are dulled-edge steel shinken, however, so I'm not sure if he even makes zinc-alloy blades.

Maro
11th October 2007, 01:03
I have a nice dent in the end of my iaito (same problem as Paul!). I'll post some pics next week - you can clearly see the layers. It is also a Beryllium/Aluminium iaito.

pgsmith
12th October 2007, 20:29
After several million nukitsuke & noto, I'm fairly certain that I would see at least some sign of wear if the polished surface was plated.
Not necessarily. I've been using my current iaito regularly since 1996, and the only evidence of wear or plating is where I filed the kissaki. If it weren't for that, I too would swear that it wasn't plated. (I know this because that's exactly what I did a number of years ago! :) )

yoj
15th October 2007, 10:06
And in any case, if it wasn't plated, surely you would see some oxidization of the aluminium?

Ken-Hawaii
15th October 2007, 19:46
Funny thing about aluminum, Jim - its surface is always oxidized. The skin forms within just a few seconds, but appears the same as pure aluminum (not that I've ever seen the pure surface). And with the zinc or beryllium alloyed to it, you wouldn't necessarily see any difference, anyway.

yoj
15th October 2007, 23:21
Ken, I briefly wondered if the alloying would have some effect, like in stainless steel, but realised i didnt have a clue ;-) I didnt realise it was that fast though, the oxidized ally I've seen has usually been on decade or older auto parts ;-)

Ken-Hawaii
16th October 2007, 00:03
Yeah, Jim, that's the main reason that you can't weld aluminum with a standard oxy-acetylene torch - the oxide skin forms so quickly that flux won't stick. You need to use a helium-arc welder so that you're flowing inert gases over the weld joint. I've heard oxidation forms in milliseconds.

I'm still trying to find out how zinc/beryllium & zinc/aluminum alloys are treated, but no luck so far....

yoj
16th October 2007, 00:17
Yeah, Jim, that's the main reason that you can't weld aluminum with a standard oxy-acetylene torch - the oxide skin forms so quickly that flux won't stick. You need to use a helium-arc welder so that you're flowing inert gases over the weld joint. I've heard oxidation forms in milliseconds.



or pure argon in a mig welder, with an oversized tip, just watch out for crows-nesting...oops i've already said too much!!!