Iaito..Chrome vs Aluminum\Zinc

[Scotoe]

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 I’m looking for something heavier (880g-1100g).

Thanks!

[Maro]

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]

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]

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]

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]

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]

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.

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]

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.

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]

Originally Posted by Scotoe

...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]

Originally Posted by Ken-Hawaii

... 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.

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

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

Ahmed Hussain

[Maro]

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]

Originally Posted by Jawa

...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.