Any experience with Petrocore Polymer sheath material?

EngrSorenson

EngrSorenson

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I have a bunch of experience with leather, but I figured I’d try something different. I picked up a bit of this from FortyTwoBlades FortyTwoBlades and figured I’d give it a try. I’m used to 9 oz leather, so I know a little bit about working with stiff materials, but this stuff is stiffer. Can’t make it pliable with water, so I figured I’d ask around and see what people use or how they work it.

I’m interested in making a simple taco sheath for smallish fixed blades.
 
Heat works instead. A hot hair dryer or heat gun will make it nice and pliable. It's a lot like a hybrid of kydex and stiff leather, so a mix of leatherworking and kydex sheath techniques will do the job. All-riveted construction is fine with it, but also it can be punched and stitched like leather. If you need to glue it at all, typical adhesives won't touch the stuff, but 3M makes a double-sided adhesive tape for low-surface-energy materials that will do a good job if combined with mechanical fastening (such as if adding a welt to protect stitching and needing to tack down the edge of it, though rivets make welts unneeded 'cause it's so cut-resistant.)
 
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It’s a pretty tricky substance to work with, but I can attest to the fact that it makes a decent sheath, and I like the price compared to leather. This one is weltless, which is not something I’d normally consider, but this stuff is so stiff I think it’ll hold up.
 
Heck yeah--great result for your first attempt, no less! And yeah it has some eccentricities to it, for sure, but a lot of advantages as well, not the least of which is the low cost! It does pick up cosmetic scuffs and scratches fairly easily, but once it gets enough of them it has a lot of character, almost like building up a patina on carbon steel, and has a nice industrial look.
 
Another thing I like about this material is that it always flexes outward. Sheathing the knife doesn’t feel like it could cut or stab through the sheath. It stays out of the way. My leather punches worked great on the stuff, too.

Saddle stitching it was a real pain, because it’s less forgiving than leather, but if I had found my speed stitcher, it wouldn’t have been a problem.
 
Yeah I recommend chiseling the stitching holes and glover's needles, possibly with rubber-jawed pliers. I typically suggest facing the concave faces of mating panels together for the tightest and most attractive fit.
 
The stitching is currently a little proud- I typically cut the leather to allow for the thread in areas where the thread will be rubbed by the knife handle.
I'm wondering if I can't use some kind of cold chisel to make little valleys for the threads?

I'm going to try it out on a scrap and see if it works.
 
Because of how thin it is you might struggle with doing that without causing distortion, but it's also the reason why I normally would use a flat-backed compression rivet or two in that context.
 
Just the 60 mil thickness. In plastic film industry standard increment changes in its thickness range, thicker makes it too stiff and difficult to process and thinner would mostly be appropriate for light duty only and for more flexible elements. 60 mil strikes a balance where it's workable to a leather-like degree, semi-flexible, and suitable for a range of common fastener types used with fabrics or leather, while being extremely protective and cut resistant to the point where a welt isn't needed.

I hope to be able to offer it in different colors, eventually, including "milk jug" translucent.
 
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FortyTwoBlades said:
Just the 60 mil thickness. In plastic film industry standard increment changes in its thickness range, thicker makes it too stiff and difficult to process and thinner would mostly be appropriate for light duty only and for more flexible elements. 60 mil strikes a balance where it's workable to a leather-like degree, semi-flexible, and suitable for a range of common fastener types used with fabrics or leather, while being extremely protective and cut resistant to the point where a welt isn't needed.

I hope to be able to offer it in different colors, eventually, including "milk jug" translucent.
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Couple more questions. Is it more flexible and easier to work than kydex? And do know if it will scratch knife blades like kydex has been known to do?
 
Scott Hanson said:
Couple more questions. Is it more flexible and easier to work than kydex? And do know if it will scratch knife blades like kydex has been known to do?
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Won't scratch, and much more flexible/easy to work. It's like a very stiff leather. The only way it'd scratch a knife would be if something scratchy somehow got down in the sheath, and then it's not the material at fault for doing it. If anything, the PetroCor is the material that's prone to scratching, but like I mentioned once it gets enough of 'em it has a nice industrial look. You can heat-mold it like Kydex but it isn't necessary, and more commonly I'll just take a heat gun to certain zones of it when I want to remove a bit of pinch or to flatten a fold. It can be cut with sufficiently sturdy shears (I use my Humboldt shears to cut it by hand) but is something like easily 5x more difficult to cut than leather, especially with glancing cuts like from a knife being drawn from it since it's sort of self-lubricating and makes the knife slide more than bite in. While I'm unsure of the hardness of our particular material, the Shore hardness of HDPE ranges 63-67 on the D scale while Kydex is 77.
 
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FortyTwoBlades said:
It can be cut with sufficiently sturdy shears (I use my Humboldt shears to cut it by hand) but is something like easily 5x more difficult to cut than leather
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Can confirm- I used a very sharp Dexter Russel rubber knife to cut mine, and I found that it was very difficult, requiring two passes to get all the way through the 60 mil thickness.
As tough as it was to cut, it was reassuring.
 
You may find that if heavy duty shears aren't available to you that things like "slot cutter" punches work nicely with a mallet. It tends to punch very well.
 
FortyTwoBlades said:
You may find that if heavy duty shears aren't available to you that things like "slot cutter" punches work nicely with a mallet. It tends to punch very well.
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I mean, I've been eyeballing those Humboldt sheers for a while now.
Maybe I just pull the plug on one if I'm going to be making more sheaths and stuff from this material.
 
I literally have 4x sets of them that see almost daily use between the household and workshop, and I often see a "normal" pair of household scissors and find myself baffled that people manage to find any use from them at all because of how easily splayed they are lol--good shears do really make working with PetroCor a lot easier.
 
I've used a bunch of it. I made a sheath for a pass around, the biggest difficulty was in getting my waxed linen to hold up for a saddle stitch. Pretty sure David Mary David Mary still has it.

The sheath I made for my corn machete is just a piece folded over with paracord run through a bunch of holes I made with a SAK awl, and the bottom is wired shut with some old copper. It's crude, but it works fine.

There's also a small piece that I keep with my flint knapping tools that gets wrapped in buckskin for pressure flaking.
 
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