Chiburi-

Hello all,

There has been a discussion in another thread about chiburi and what effects blood has on a sword. During this discussion, it was my contention that chiburi was good enough to remove excess amounts of blood from the sword, which could then be resheathed and properly cleaned later (some of the posts discussed the need to wipe the sword before resheathing it, or the sword would rust). My claim was challenged by some people who are obviously very knowledgable, and, therefore, the issue seemed worthy of further research.

First, I contacted Dr. Ben Horenstein, a professor of organic chemistry at the University of Florida, to ask him if he could shed light on what blood might do to a sword. A few people on this forum have said that blood is extremely corrosive (even as corrosive as sea water). According to Dr. Horenstein, this is not the case. Blood contains nowhere near the amount of salt that sea water does and the salt compounds are chemically different. Blood, as it turns out, is slightly more corrosive than pure water, and probably just as corrosive as most tap water in the U.S. Blood, however, has one unique quality that makes it an unlikely corrosive element--it dries too quickly when exposed to the atmosqhere (more on this later).

After hearing this, I was ready to try an experiment. One of my students (Chuck Seegert) is a candidate for a Ph.D. in biomechanical engineering at UF, and an extensive part of his coursework is materials engineering. He basically has to know how metals and other materials interact with blood and other bodily fluids. He suggested I test my theory on one of my swords. I currently have two Paul Chen swords, both of which require the same amount of care as a shinto I once owned and a koto I used for an extended period of time. Chuck acquired too viles of human blood for our experiment.

First, I wiped the oil off of a section of my sword in a direction consistent with a cut. We then poured both viles on the blade and let them sit for a few seconds. I performed our style's version of chiburi (the blade is lowered at a 45 degree angle pointing to the ground and held for about five seconds so that the excess blood can collect on the ha, then a single, quick flick of the wrist is used to shake off that excess). When it was done, a lot of blood had come off, but there was still quite a bit of blood on the blade. It was sticking to it like glue. I then performed noto, essentially sheathing a bloody blade. This part of the experiment was performed at 11:45 a.m.

It was my intention to carry the sword around consistent with the manner in which it is worn and wait for several hours to see what would happen. Chuck, however, suggested I check it within ten minutes. I did so, and, to my surprise, most of the blood was dry. I examined the sword for about 15 seconds before resheathing it. I checked it again at 20 minutes and every bit of blood on the blade was dry.

At 7:00 p.m. I met up with Chuck to finish the experiment. I removed the sword from the saya and began to clean it. The first wipe turned into a bit of scrubbing to remove the dried blood. We then examined the blade and Chuck said, "Hmph, look at this." To my horror, there was barely-distiguishable discoloration where the blood had been. Chuck saw that I was worried and laughed. He then explained that the blood had bonded with the remaining dirt and oil and had essentially left clean marks on the blade. I powdered up the blade and wiped it clean twice. Sure enough, the entire blade was now all clean and a uniform color. There was no corrosion and no rust. I oiled the sword and put it away.

It has been two days since this experiment and there are still no signs of rust or corrosion. The blood simply dried too fast to do any damage.

As of now, I am satisfied with my original assertion that chiburi will work to remove excess blood from the blade, and the blood that remains, although it is a bit more than I thought it would be (my thanks to Paul for pointing out that cutting removes oil) can be cleaned later.

As for wiping blood off the blade at the time of the kill, a few things occured to me. If you used the clothing of another person (as was a suggestion in another post) you would be removing a great deal of oil along with it, which is needed to protect the sword from humidity. Living in Florida, I have to keep my swords well-oiled constantly. As for keeping an oil cloth on you to wipe with, I have to put oil on them each time I use them or I'm afraid I won't get enough oil on the blade. Carrying around an oil cloth- I would be afraid that it would dry up.

I hope this information is of value.

Jason Backlund

[Scott Irey]

This is an interesting experiment Jack, but I have to point out that there is a vital factor you are leaving out. To simply pour blood onto the sword is not enough, as it does not accurately simulate the blood and other matter that would be left on the sword after cutting into a living (or dead for that matter) target. When cutting into a fleshy target, you pass through skin, then a layer of fat and finally into muscle. The layer that needs to be paid attention to here is the layer of fat. What happens when a sword cuts into flesh is the layer of fat leaves a fatty film on the blade, which traps moisture (blood) and prevents that moisture from dehydrating so rapidly. The combination of this trapped blood (and other fluids) with the film of fatty material leads to corrosion if left unattended. I was told this by some former Japanese soldiers who "had experience" by folks who have tried tameshigiri on animal carcasses and finally saw it for myself when a friend cut himself severely during a tameshigiri accident. The sword was left unattended for several hours while he was being stitched up, and when it was finally retreived and cleaned, a film of still moist blood and fat was removed (not an easy thing to do, a solvant was used to finally clean it off) and a stain was evident (darker than surrounding metal). Now if you or anybody else would like to replicate my friends experiment, I would certainly like to hear the results

Another factor I feel has been left out of this dicussion as a whole, is that the rate at which a given sword will stain probably has a great deal to do with the composition of the steel as well as how recently the sword has been polished.

Regards,

Scott

[Richard Elias]

It was my understand that wiping off the excess blood (and other matter) wasn't just to prevent the blade from being damaged but also to stop the material from getting inside the scabbard. It could possibly serve as a glue to prevent, or at least inhibit, a swift draw of the blade if it dried while making contact with both the blade and the inside wall of the scabbard. This of course depends on the fit of the scabbard, but I would imagine that one would not want to get a build-up of such stuff inside it either way.

Scott,

I'm glad you brought this up. I didn't have room for this in my first post. I had no way of testing an actual cut, but I did bring this up to my friend. I discussed the deer carcass scenario with him, as it was posted before on the other thread.

Fat is not a greasy, filmy layer in the body. The film of fat that you get from cutting a piece of meat is a result of decomposition. If you've ever cut yourself deep enough to reach the fat layer (deep enough to need stitches) you didn't find a greasy substance that would leave a film- it's composition is different. However, as soon as blood stops pumping oxygen to the fat cells, decomposition begins. Even if you cut it 30 minutes after you killed it, cutting a deer carcass would be far different from cutting a living thing. If you waited until it was cool, it would be even filmier and greasier, like it is when you cut a steak.

Also, if there was a layer of fat on the blade that sealed in moisture, it would not cause corrosion. In order to have corrosion, you need a corrosive substance and you need oxygen. There is not enough oxygen in blood to start rusting the blade while it's still moist. It would need to get it from the atmosphere, and that would cause it to dry quickly. Basically, if the blood isn't drying, it isn't corroding either. One reason metal implanted into the body (pins for knee surgery and such) has to be stainless steel is because blood is constantly bringing oxygen in contact with the metal and causing corrosion, but this takes a long time. Blood taken out of the body (after a cut) wouldn't do this. This is the same for other fluids, including water. If the fat trapped the moisture, it would be okay. If not, it would dry and then be okay. The true danger to a sword is acidic compounds (like those found in finger prints) and prolonged exposure to moisture in the air.

As for the steel composition- Japanese swords show rust quickly because the stress from forging leaves tiny fissures in the metal that give oxygen and moisture more surface area to work in. These fissures can show themselves as a grain in the steel if your sword has large ones. The sword I used in my experiment has a very distinguishable grain in the ji. It is very prone to rusting quickly and requires constant attention.

I don't know what happened to your friend, how he cared for his sword or the circumstances of the incident, so I would be hesitant to draw any conclusions about what happened to his sword. The dark stain he saw could have been the same discoloration that I saw (essentially, really clean spots). It took two powder applications to get the rest of the blade that clean. Are you sure those dark stains are rust? If what happened to your friend's sword is what you are saying, only a controlled experiment could truly tell. I tried to do that the best I could. The only way to truly simulate cutting a real living thing is to cut a real living thing. I will stick with bamboo.


Richard,

The point of my original post on the other thread was that chiburi would keep excessive amounts of blood from dripping into the saya. That worked in my experiment. The fitting of the habaki into the koiguchi is such that the mine rests on the wood in the saya and only a very tiny portion of the side of the blade will touch it occaisionally if it shifts. Basically, if it doesn't drip off the sword into the saya, it's not going to get on the wood. If it did, your major problem would be wood rot. As for preventing a swift draw, it would take a huge amount of material to do this. As you put your sword in the saya, you'll notice that there is a great deal of space and freedom of movement present all the way up until the habaki seats at the koiguchi. Perhaps the glue effect would work if you got a lot on the habaki, but I'm not sure that blood, or any other fluid you would get from a cut, would do that. Then again, excessive amounts of blood absorbed into the area of the koiguchi could cause the wood to swell making it tougher to free up the sword, but chiburi should take care of that.

Jason Backlund

[Richard Elias]

My post was not intended to detract from the merrits of chiburi, it does work. It's just that it wasn't done just because of what it might do to the blade but what it might do to the scabbard.

The fact of the matter is, by your own testing, chiburi does not remove all of the blood from the blade. Therefore chiburi alone should not be relied upon, and the blade should be wiped clean before being placed back in it's scabbard. It would seem irresponsible, and bad form, to do so. Not, I mean, for every day practice, but if your actually cutting things. In our style that is what is taught, it's part of every form. To not wipe the blade is to leave the form incomplete.

Excellent posts everyone!
Great thread.

Richard,

My reservation with wiping the blade clean is that that action can remove oil that is needed to protect the blade from humidity. It also seems to me that if you were carrying an oiled cloth for that purpose, it wouldn't stay that wet throughout the course of the day. During my experiment, based on what I observed through lack of smearing or change in the appearance of the blood, little or no blood came off the blade into the inside of the saya. Therefore, putting away the sword with the remaining blood on it does not seem irresponsible to me. It seems to be a matter of waiting until you can do the job right.

Our system does not teach wiping the blade after chiburi and before noto. Then again, if you were going to wipe the blade, why would you need chiburi at all? I suspect that some samurai found chiburi adequete and others didn't. After all, it only takes one person to start a ryuha. We'd like to think that all kenjutsu headmasters agreed on what works and what doesn't. Perhaps one kenjutsu master didn't feel the need to wipe his blade clean before resheathing it, instead chosing to clean it later. Perhaps a different master was a bit more paranoid about ruining his sword and saya and wiped it clean each time. Every student thereafter might just be doing what the founder of the style felt was adequate and coming up with all sorts of reasons and analyzing all sorts of experiences in favor of their style's convention. My sword and saya are still in good shape. Perhaps yours are in a little better shape. Perhaps not. I am a firearms instructor and every time I shoot, I strip and clean my pistol. Many excellent shooters I know choose to clean their pistols only a couple of times a week. Their pistols fire just as well as mine does. Nevertheless, I find myself cleaning it every time I shoot, just in case.

With respect for all,
Jason Backlund

[Doug Stryker]

Man, this is starting to sound like rocket science. I love this! You guys are amazing with how much you know about chemical reactions, anatomy, and such. Thank you for sharing your knowledge and taking the time to explain it all so well.

Let me make sure I'm understanding this correctly. If the fat holds in moisture, then the blood won't dry and the steel won't rust. And if it doesn't hold moisture, then the blood dries and the steel won't rust. And blood, on its own, dries too fast to cause corrosion.

So what causes the rust? Is it the combination of blood, fat, and time? Or is it more variable than that? Does the pH of blood vary from person to person? Is it due to the porous nature of each individual blade that might make one more prone to rust than another?

Regards,
Doug

And does this guy perform chiburi afterwards?

[Richard Elias]

Jason,

Well met.

When I was writing my last post I was almost going to use the pistol analogy as I view my sword the same way.

The wiping of the blade is simply to remove whatever doesn't come off during chiburi. Incidently we don't use an oiled cloth for wiping the blade, we use a piece of paper (washi) that was traditionally carried tucked into the kimono as a part of the regular costume of the period. Depending on how you've been using the sword...If you've only used the monouchi to cut with- the act of wiping the blade begins at the base of the sword where it meets the habaki, and is then drawn the full length of the blade. The paper will collect and spread the oil down the blade. As the paper comes in contact with the blood (or whatever) and absorbs it and wipes it away the remaining oil-coated portion of the paper re-coats the blade with a thin layer of collected oil. Even more so if you have a heavily oiled blade. Just as it usually takes more than one wipe to clean off all of the oil when you are going throught the regular sword cleaning process.

I do have some questions about the humidity concerns:

If humidity is a concern then what of the blood?
If the blood is on the blade when it is put in the scabbard then isn't the moisture that comes from the drying blood then trapped in the scabbard with the blade along with whatever air is also in there?
If you are then counting on the scabbard to absorb the moisture would it not be doing the same for the moisture from the atmosphere?
(Unless you are swinging your sword around without ANY oil on it and not putting it back in the scabbard for some time)
If you are going to wait until a later time to remove the remaining blood for when you're giving the blade a thorough cleaning, then why be concerned about the minor film of rust that may acumulate as it would be removed by the application of uchiko during the cleaning as in your example with the blood.

Now I haven't done the sort of experiments that you have, and the climate where I live is not so humid as Florida so my sword is not at the same risk as yours would be. But you've piqued my interest.

Doug,

Lipids (fatty acids and related compounds) are everywhere in the body, including blood. At the body's temperature, certain lipids are chemically very fluid, so that they can pass through cell membranes, and don't have a filmy residue. If you've ever cut yourself deep enough to reach the layer of fat, the only fluid you felt was blood. As the temperature drops and the cells die, certain saturated fats like those found in animals (non-saturated fats are found mostly in plants) will grow increasingly less viscous and more like the film that was mentioned in a different post. Cutting into a living person, the fat that is left on the blade would be indistinguishable from the oil on the sword (the oil being a type of non-saturated fat derived from a plant). As fluid as this fat is, and as little of it as there is compared to blood, it is doubtful that it would stick to the sword in such a fluid state (especially when the blood would).

If, however, it did stick to the sword and there was a layer of fat, that wouldn't matter much. Lipids are for the most part not water soluble, so they would coat the sword and keep out moisture or keep moisture in where it can't get to oxygen. Moisture and oxygen are the main ingredients for rust. Acidic compounds can also corrode steel, but you wouldn't get much of that unless you cut into the digestive system and stayed there for a while. Blood is not acidic and so its pH level is not a concern. If, however, a person took enough aspirin or alchohol, which works to thin the blood, then the blood wouldn't dry as quickly. That could be a problem for a sword because blood has low levels of salt compounds which can be corrosive.

As for steel- formed steel, like tools and pocket knives rust uniformly on the exterior. Living in Florida, all of my tools are covered in rust, but this would take forever to damage the structural integrity of the steel. Japanese swords, however, have fissures that give corrosive elements more surface area to work with. If you've ever seen a badly rusted blade, you'll note that it probably has pits where the steel has been eaten away. The more a sword is stressed during forging (a sword starts as a small block of steel and is stretched by repeated pounding until it takes the shape of a blade) the bigger the fissures and the easier it will rust. Composition of the metal is another area you can get into, but there's no easy way of explaining the significance of that.

Jason Backlund

Richard,

--"If humidity is a concern then what of the blood?"

Blood dries quickly as part of its chemistry. It's not like humidity at all. If you repeatedly poured fresh blood on a blade, that would rust it. Otherwise, there isn't time for real damage. At least, that's what my experiment seemed to show over a seven-hour period. I wouldn't hold off any longer before giving it a good cleaning.

--"If the blood is on the blade when it is put in the scabbard then isn't the moisture that comes from the drying blood then trapped in the scabbard with the blade along with whatever air is also in there?"

As I understand it, blood doesn't evaporate and release moisture when it dries. And I've never owned a sword that had an air-tight fitting between the habaki and koiguchi. If I did, I wouldn't have to oil the thing so much.

--"If you are then counting on the scabbard to absorb the moisture would it not be doing the same for the moisture from the atmosphere?"

The saya is exposed to atmospheric moisture, and I don't know if the wood is treated or not, but it's apparently not getting enough moisture to damage the wood. As for the sword, the oil keeps the moisture out.

--"If you are going to wait until a later time to remove the remaining blood for when you're giving the blade a thorough cleaning, then why be concerned about the minor film of rust that may acumulate as it would be removed by the application of uchiko during the cleaning as in your example with the blood."

I'm not quite sure what you mean. There was absolutely NO rust during my experiment, and I would be concerned about any amount of rust accumulating on a sword. I fight to keep any rust from developing as hard as I can. Uchiko powder may remove a bit of rust in its earliest stages, but I wouldn't chance that if I didn't have to.

Jason Backlund