Unknowns


Lately, I’ve been thinking of wrapped handles – especially after seeing some of the beautiful work kestrel does, and some of the Japanese-style wrappings on Michael Bell’s sword mountings. What’s something tough, beautiful, interesting, weather-proof?

Carbon fiber nanotubes, of course!

I got a piece of carbon fiber cord on Ebay, and it’s beautiful stuff. My plan is to leave it tied around the porch rail until next summer and if it still looks good, maybe I’ll think about using it on a handle. One of my pet peeves in the current knife-making scene is a lot of people just use stuff without thinking about its weathering properties. I’ve seen people assembling blades using glues that have no shear strength at all, and finishing them with urethanes that are incompatible with the silicones they are using elsewhere. After posting a few compatibility charts on the beginning knife-maker list on facebook, I gave up. By facebook’s nature, a problem becomes a moving target as whoever gets interested in the field drops in, starts from scratch, and asks the same questions immediately.

I got to the point where I was using my friend Andrew’s stock response, which was: “hours in the darkroom can save you minutes in the library.” This is how curmudgeons are made.

Anyway – the carbon fiber cord has to be felt to be believed. It looks like, and feels like, fine silk – but it has as much “give” in it as stainless steel cable. I.e.: none at all. It feels like you could tow a tractor with it. (“hey, that gives me an idea” as he looks out over the field at the neighbor’s tractor)

But then I got to wondering: is it dangerous to have nanotubes floating around in your environment? If I recall correctly, we don’t entirely understand the process whereby asbestos causes mesothelioma – other than that the fibers ‘irritate’ cells (I assume that means “penetrate and kill”) which increases the body’s tissue self-repair rate, while also increasing the chance of DNA getting damaged. Boom: cancer. I lost a friend, Dan U., to mesothelioma in 2012 – he was one of those once-strapping lads who was too tough to wear a filter mask while he worked on an asbestos abatement project to get college money. He was dead at 40.

This seems to me to be an unknown. I did some searches on medline and it appears that “we don’t know yet” is the consensus. Which means, “maybe having carbon fiber knife handles is a bad idea.” It might not be a bad idea, but it might be the equivalent of thinking “wow this fire-retardant asbestos’d make a great knife handle because it’s fire retardant and that’s just tactical as heck!” I did more research and one thing I saw, which I came to dislike, is experienced knife-makers teaching other people how to take a chunk of carbon fiber and turn it into airborne dust particles using a belt sander. If you’ve never used a serious belt sander, you don’t know what dust is (unless you have experience brushing horses, which are great big bags of farts and dust as far as I can tell) – you wind up with a layer of dust on everything and all over you. I started to wonder if knife-makers should be wearing tyvek bunny suits and positive pressure respirators while they work on the stuff. That’d sure dampen enthusiasm for that as a handle material.

Another handle material I wonder about is fossilized bone. First, it smells like a cat’s butt when you’re grinding it, but it’s porous and it’s been harboring dog knows what kind of generations of anthrax or whatnot. I don’t use fossilized bone, but a lot of people do.

I’m sure wood’s bad too. Back when I was in college I did some dagger handles in ebony, and I was hawking up black goop from my sinuses for weeks. Maybe that was a fatal injury, like Dan’s.

Dust management is a huge problem and I’m going to be getting to that, and discussing that in more detail later, but in the meantime: do any of you know about dangers inherent in raw carbon fiber nanotube material?

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I know that most applications of carbon fiber involve bonding it with some kind of epoxy or polyurethane resin. That keeps the stuff from abrading and flying all over the place, but the resins are generally going to degrade over time or exposure to the sun. Using resins for knife handles is also a big rage, but I’m not convinced that’s a great technique, either, because it may not weather well. I think I’m going to make a couple of handle slabs out of resin and tie them to the porch railing with this nice carbon fiber cord, and I’ll see if there’s anything left, this time, next year.

“By facebook’s nature, a problem becomes a moving target as whoever gets interested in the field drops in, starts from scratch, and asks the same questions immediately” – this was the problem that resulted in people writing “Frequently Asked Questions” (FAQs) back in the USENET days. [fwfaq] [otpfaq] I just kept thinking “oh no, not again. I am not writing another FAQ.” But someone’s gotta do it.

Comments

  1. dashdsrdash says

    OSHA says:

    Skin and respiratory irritation, contact dermatitis (chronic interstitial lung disease)

    where effects in parentheses are suspected rather than proven. The same effects are listed for aramid and glass fibers.

  2. cvoinescu says

    My understanding about carbon nanotubes is that we don’t know yet, but they might well “work” the same as asbestos. Any nanomaterial has the potential of being deadly in new and interesting ways — odds are we’ll learn about some of them the hard way.

    Regarding online discussions and FAQs, I found that for a hobby subject, the best approach with today’s technology is to have a bulletin board type forum (such as phpBB, for all I dislike PHP) and a wiki. The forum has a quick turnaround and is searchable, much like a mailing list, but with the added benefit of finer subdivisions of topics; and the wiki is the curated form, like a FAQ, where a small number of volunteers extract the meatier tidbits from the forum — a summary of the state of the art that’s easily readable in one take.

  3. cartomancer says

    Cured shark skin was the traditional material for sword hilt wrappings in Medieval Japan I believe. But that would probably incur all manner of ethical problems, given that most shark species are endangered now. The Romans used wood or bone mostly. Ivory for expensive display pieces. That said, very few of the non-metallic pieces of Roman swords have ever been found.

    I suppose the function and environment in which the knives will be used are significant. Kitchen knives probably won’t get anything like the abrasion and weathering that knives for outdoor work will.

  4. sillybill says

    Regardless of the health effects, you will need to find a way to keep the ends from fraying. Just tying a knot on the end won’t look good. And presumably you wouldn’t want some ugly blob of glue on the end. My tree climbing buddies and I have always melted the ends of synthetic ones such as climbing lines or p-cord. With p-cord or small lines you can just use a lighter then smush the ends into a rock or tool (warning: hot melted nylon can sticky-burn your fingers!) but with climbing line we heat up a butter knife over a camp stove and cut it smoothly. Does this stuff melt?

  5. says

    cartomancer@#3:
    Stingray skin. It’s incredibly tough and dimensionally stable stuff.

    It’s now illegal to use in some places, such as Oregon, which is a problem for traditionalist swordsmiths like Michael Bell.

    Wood is generally a wonder material. There are woods that contain natural oils (lignun vitae) that are very beautiful and durable. The current state of the art is to vacuum soak woods in resin, which seals and hardens them. I use naturally polymerizing linseed oil and plan to vacuum infuse it.

  6. says

    Wood dust is known to cause cancer in upper respiratory tract (nose cavity). Bone dust too. In addition to this, some woods are much more dangerous than others, for example grinding yew ond beld sander is definitively a no-no, regardles how good respirator one does have (I would not dare do it even with positive pressure mask).

    I would go with the assumption that very fine dust is dangerous in itself and go from there. Better safe than sorry.

    Sounds fine, but what else does A. niger make that gets through?

    Graveyards are full of such people. Toxic masculinity at its finest.

    I have no personal experience with tung oil, but alegedly it is harder than linseed oil and therefore better suitable for deep infusion into wood.

    I am currently (very slowly and irregulary) experimenting with atificaly infusing wod with silic, in effect petrifying it.

  7. says

    Fuck, that quoe should be “he was one of those once-strapping lads who was too tough to wear a filter mask”
    Sorry, my keyboard is actng up,not reacting, leaving out letters hen writing five at once, I do nt know why.

  8. Pierce R. Butler says

    Charly @ # 7: … my keyboard is actng up…

    Open it, and I bet you’ll find, most appropriately for this thread, fine particles and mystery goo.

  9. says

    @Pierce R. Butler I opened it and replaced batteries. That seems to have solved the problem for now :-).

    But perhaps I should dismember and shower it again, it has been awhile since I have done that.

  10. says

    Charly@#7:
    Sorry, my keyboard is actng up,not reacting, leaving out letters hen writing five at once, I do nt know why.

    Ever since the Vault 7 disclosures, it has been hard to get good keyboard-interposer malware.

  11. Bruce says

    I’m no expert, but I think there is no reason to doubt the reports of warnings mentioned above. Specifically relating to carbon nanotubes, probably few experiments have been done. That doesn’t count as evidence of safety at all.
    What is well established is that the molecular structure of carbon nanotubes is analogous to an infinite extension of buckminsterfullerene, or C60, or buckyballs.
    Buckyballs are a third elemental form of carbon, just discovered over 30 years ago. However, it has since been found that buckyballs are naturally formed in small amounts in natural wood fire soot. And that buckyballs and natural wood soot are highly carcinogenic.
    I wouldn’t worry about using an item made of carbon nanotubes myself. But I wouldn’t want anyone to put their health at risk by being near anyone who was sanding or grinding nanotube materials. Do you want to be a human experiment on a substance there is already reason for caution around?
    I think it is fairly safe to be in old buildings. But I wouldn’t want to wash the clothes of anyone who dismantled an asbestos wall, for example.

  12. lorn says

    A tale from the past: The weapons engineers came out with this new carbon fiber panels that was supposed to revolutionize the skins of aircraft. Super-strong, immune to corrosion and fatigue, light and resistant to dimensional change when temperature changed it was going to make all our fighters better. So they started substituting it for the aluminum panels.

    A week or so later, in another part of the rework facility, where they test. repair and recalibrate electronics things were not going well. They had been stymied by a great number of intermittent readings, shorts, circuits that were burning out. Gear that was shorted would clear without explanation. Assemblies tested good would fail and, in a few cases, burn up for no apparent reason. At first it was attributed to power surges, operator error, or carelessness but even operation witnesses and using best-practices to the letter were failing.

    It was only when some electronics in the area handling the carbon fiber skins failed that an answer was found. To fit the skins to the aircraft they crews were drilling and sawing the skins just like they did with the aluminum ones, This liberated carbon fibers so light that that they floated on air currents. These tiny fibers were making their way to the electronic shops and, being conductive, causing shorts. Shorts that were difficult to track because even breathing on the fiber could cause it to move. They also cause a few minor fires when the carbon creating a short could glow red-hot and burn its way though the traces and into the board.

    The DoD is said to use carbon fiber strings in warheads on cruise missiles to destroy transmission lines. The carbon fibers cause a short and heat up enough to melt through the aluminum and steel power lines.

    The problems at the rework facility were largely solved by using HEPA vacuums to collect the fibers when the panels are machined. The doors to the electronics shop were also gasketed and air filters installed to collect any stray fibers.

    All went well until a second issue popped up. This time it was a matter of corrosion. You see, carbon fiber doesn’t corrode. But it does conduct. And it is in the galvanic series. Way, way up at the top. Pretty much everything sacrifices itself to protect that stuff. And, to make matters worse, even thin bundle of carbon fibers has a surprising amount of surface area. A large surface area of highly noble material next to a much less noble material is an invitation to serious, and seriously fast, galvanic corrosion.

    None of these issues has stopped the DoD from using carbon fiber. There were issues but, after a considerable amount to head scratching, the issues were understood and adjustments made.

    Perhaps none of these will be a problem. I’m certainly no expert. Something to think/ ask about.

  13. cvoinescu says

    @14: No doubt.

    I’ve just realized: you bought carbon fiber cord, not carbon nanotube cord, right? Carbon fiber is not a nanomaterial, and has been around for a while.

  14. John Morales says

    My plan is to leave it tied around the porch rail until next summer and if it still looks good, maybe I’ll think about using it on a handle.

    Excellent empiricism.

    (Presumably where it’s exposed to sunlight)

  15. says

    @lorn #13 Great tale. You reminded me of a similar one form plastic manufacture. There are moldable plastics (i.e. meant to be melted and pressed into form to let solidify) out there that are not filled with glass fiber, but with carbon fiber. Allegedly they are a bugger to work with for the reasons you mention – some carbon dust gets always lose and it floats and because it is conductive, it can shortcut machines.
    I have not known that carbon can act as noble metal in a galvanic series. That would definitively mean you do not want to assemble it onto any kind of knife, not without a protective, non conducting layer between the carbon and the fiber.

    @Marcus, I forgot to write this re: persishableness and constance – linseed oil does degrade in light (even visible light, not only UV) and yellows too, so I do not think it is an improvement over modern resins in this regard.

  16. says

    Charly@#17:
    linseed oil does degrade in light (even visible light, not only UV) and yellows too, so I do not think it is an improvement over modern resins in this regard.

    Huh! I have never noticed that.

    Wait – yes, I have. I’ve always just chalked it up to “natural darkening of the wood.” My maple handles that are decades old, have a lovely carmel color. In fact, I tend to assume my woods will darken over time, and choose them accordingly. Now, I feel like a complete dumbass. “Natural darkening of the wood.”

    I do have the gear necessary to do vacuum infusion, so I will have to experiment with resin someday. Maybe in a few years. I do want to see what black resin does – I have dyed many handles with feibing’s leather dye, which works great, but it tends to leave black smudges here and there for the first couple years you carry the knife.

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