Sheaths: Nylon Vs. Leather Vs. Kydex?

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Mar 9, 2012
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I need some advice. Everyone I speak with seems to have widely varying opinions of which type of sheath is best for a knife. In my case, there's 2 knives I'll want custom sheaths for. One is (I think) polished 1065 high carbon steel (10" blade). The other will be INFI (11" blade). There are obviously pros and cons to each type of sheath.

I live in a part of Canada that has bitter cold winters and hot humid summers. I'm therefore a little bit concerned about extreme temperatures. Keep in mind here that what I'm seeking is not affordability, but rather versatility, performance & longevity. Also, if anyone could suggest reputable custom sheath makers, I would be grateful :)

I'll list what I -think- that I know. (Please correct me if I'm wrong, and feel free to add anything I've missed! It's important to me to make the right decision!)

Nylon:

- May dry quicker than leather

- (In my limited experience w/nylon) can fray easily

- I honestly don't know anything else about nylon :S


Leather:

- Strong resistance to cold

- Dust & moisture particles can build up on the inside of the sheath easily

- May become moldy in a humid environment

- Tanning salts (in some sheaths) can potentially oxidize brass on knives (my 10" has a brass guard and pommel)

- Comfortable

- Absorbs & holds water (must be bad for rusting?)

- Quiet (quiet is good)

- Aesthetically pleasing

- Skin acids eat away at the material (????)

- Sheath can lose shape with too much moisture? (From water, oil, etc?)

- Drying too quickly will cause sheath to harden (does it become brittle?)


Kydex:

- Noisy

- Weak against impact/cracks easily

- (often) highly versatile for carrying options

- Sheathing/unsheathing dulls blade quicker (????)

- Exposure to heat will change mold of sheath

- Otherwise temperature sensitive (can shrink and swell apparently?)

- Cleans very easily

- Scratches your blade (????)


*No doubt there are treatments available for leather to reduce moisture retention????*
 
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They are an ongoing experiment for myself as well, but if you have the money, maybe you would want to have a couple made. i had a kydex one made by Mike Sastre over at river city sheaths that was perfect for what I used it for, but I still have the molly compatibly nylon sheath that I want to attach to my pack, so I can have multiple places to sheath it while I'm on the trail. Experiment brother, but spend that little extra and have a better experience is my advice.:thumbup:
 
I've made tons of leather and kydex sheaths. I really don't think the differences matter.
 
My $0.02

Leather:
From a decent maker, leather is an amazing sheath material, the most beautiful & comfortable & quiet of the options as well as highly functional, able to provide secure retention without harming a delicate blade edge and still resist cutting. My Cattaraugus 225Q, WC Davis Loveless-style hunter, & SRKW Rodent Solution are all in leather sheaths, and I prefer leather-sheaths for folding knives as well (when a pocket-clip is a poor choice). However, it's organic, subject to rot/decay/molding if left sit in an overly humid environment. Treatments limit this but do not eliminate it. It retains moisture more easily than the others, be it water or other chemicals which can have ill effects on the sheath itself as well as the blade (unless the blade is coated already, reducing this problem). If left too wet, it can warp. It also loses that moisture and if left too dry can crack. It abrades easily (surface rubs away) which weakens it and makes it more susceptible to the elements. It can get stained or dirty and be more difficult to clean/restore. While it resists cutting, it is still easier to cut through than a plastic insert or kydex sheath. And finally, a good quality leather sheath is substantially heavier than a kydex or nylon sheath for the same knife (in my experience), and is often more expensive, but paying that price seems more worth it to me than paying a similar price for plactic.
My conclusion - choose leather for knives that you desire to give a "classy" appearance too and which you will take care of by making sure that the knife is protected and the sheath is not left to die of exposure (so to speak).

Kydex:
Kydex is light-weight, relatively inexpensive (shop around), impervious to the elements, but somewhat noisy and quite spartan & ugly left alone. Kydex is a platform on which to customize a sheath with accessories - tek-lok, molle-back, kit-pouch, drop-leg loop, etc. The options are numerous, giving the kydex platform maximum versatility... but those options add-up in price. To date, my only kydex sheath (from azwelke) holds my SRKW HRLM, and it has been accessorized with an ESEE molle-back and pouch, though I also have a tek-lok I can use with it. Naked kydex is stiff and uncomfortable imho, especially since most makers provide sheaths substantially wider or longer than the blades they hold, but kydex is also thinner than a leather sheath, providing a lower profile on the body. The noise level of kydex comes from hitting it against other objects or the blade when sheathing/unsheathing, and there is the click of a tight-fitting sheath snapping into retention. Honestly, it is not that loud, just louder than leather, and a little mineral oil reduces this substantially.
Kydex doesn't need much in the way of care, and no natural temperature mine has been exposed to in Oregon, Minnesota, Michigan, or Wisconsin has affected it in any negative way. Extreme cold has made it less flexible, heat makes it more flexible, but it is highly impact resistant and has never cracked in the cold nor become pliable/warped in the heat.
In terms of damaging the edge of a knife, I've not experienced this. Kydex is sufficiently cut-resistant that my edges do not penetrate far enough in by accident to be subject to side-loads that could fracture out a thin edge, but the material is not so hard as to dull the edge on contact. With a good HT, your edge should be fine.

Nylon & Canvas cloth:
Cloth is a common over-sheath material for knives, i.e. there is usually (or should be) a plastic (possibly kydex) insert for the blade. Nylon is not as cut or abrasion resistant as leather or plastic and should be protected from the edge of your knife. Nylon thread can absorb water by capillary action but does not retain it and is not subject to rot/decay, it remains soft and flexible (will not crack), cleans easily, is very light-weight, and can be easily repaired with needle&thread. A nylon sheath can be used to carry a variety of knives/tools by simply exchanging the plastic insert. Appropriately placed rivets and molle-strips on a sufficiently stiff backing make nylon the perfect upgrade to naked kydex. There are numerous commercial purveyors of nylon sheath-material and accessories including Condor, Blackhawk, & Maxpedition. ESEE offers nylon/canvas accessories for its knives. I carry my SYKCO 511 in a SpecOps Combat Master with the liner custom-fit to the blade - it's durable, quiet, versatile, light, and comfortable.
My conclusion - choose nylon and/or kydex for knives requiring maximum sheath-durability (or which you don't want to have to ever pay much attention to) and when you don't care about how it looks...
 
Chiral,

Thank you very much for all the great info! From the way you've described nylon and custom kydex, it sounds great! If I'm not mistaken, the old style Fehrman sheaths were actually leather lined with kydex - something that, to me, seemed very unique.

Considering how heavy my blades already are, a lightweight sheathing option is becoming more and more attractive... If I can find someone who can/will make a nylon sheath lined with kydex, I think I'll be giving them a shout :)
 
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