I am always looking for ways to improve my slingshots. One way is to make the pouch out of an exceptionally strong leather so that it can be made as light as possible. Saving pouch weight can make a substantial difference in velocity, particularly when shooting light projectiles.
I did some research and asked some people I know who are in the leather trade for suggestions as to what kinds of leather would offer the highest tensile strength. I am still waiting for samples of falconry grade kangaroo leather, salmon leather and some other potentially superior leathers, but I am ready to publish some interesting test results for your reference and to stimulate new ideas.
My method was to take a strip slightly wider than 10 mm and to use a round hole punch to create a weak point of 10mm across. I incrementally applied pressure from a chain hoist till the leather failed. If the scale maxed out first (>30Kg), I would reduce the width with the round cutter to 3-5mm and retest, scaling up the break test tension proportionally.
Name: Upholstry leather Animal: Bovine/ Cowhide Split: top grain Part of hide: believed to be bend Tanning: believed to be vegetable tan, chrome re-tanned, aniline Post treatment: None Weight: 0.10g/cm² Thickness: 1.25mm Tensile strength: 22kg/cm width Comments: Currently used on my Flatbands. Cheap and plentiful.
Name: Saddle leather Animal: Bovine/ Cowhide Split: top, buffed Part of hide: back/side Tanning: vegetable tan Post treatment: saturated in oil based treatment Weight: 0.15g/cm² Thickness: 1.60mm Tensile strength: 62 kg/cm width Comments: Bought from a craft merchant for use in making tooled leather articles. Can be skived. Plentiful locally.
Name: Deer leather Animal: Deer (wild cull) Split: top Part of hide: unknown Tanning: Chromium Post treatment: none Weight: 0.05g/cm² Thickness: 1.05mm Tensile strength: 12.5kg/cm width Comments: A little stronger and much lighter than upholstry leather. A reasonable choice if I want a lighter pouch. A bit too stretchy. Tendency to tear. Expensive.
Name: Suomi pressed leather Animal: Bovine/ Cowhide Split: believed top Part of hide: unknown Tanning: vegetable, pressed Post treatment: saturated in oil based treatment Weight: 0.28g/cm² Thickness: 2.43mm Tensile strength: 70kg/cm width Comments: A very strong leather, but inflexible. Very hard to cut. Expensive.
Name: Lapp leather Animal: Reindeer Split: believed top Part of hide: unknown Tanning: Vegetable, traditional, pressed, buffed Post treatment: saturated in oil based treatment Weight: 0.20g/cm² Thickness: 2.35mm Tensile strength: 66kg/cm width Comments: A very strong leather, but inflexible. Almost impossible to cut; had to be cut on a band-saw. Very expensive. Special order.
For now, I will continue to use the upholstry leather.
Yes that's why I gave the width as well, but seeing as I don't plan to skive the leather, and the data would not be valid proportionally to the thickness if skived, the practical units are kg/cm. Sorry about the use of metrics. For my first few months here I dutifully converted all the measurements into American (Imperial) units, but I have trouble doing science in anything but metric units.
I also gave the weight per surface area, which is how leather merchants grade leather thickness, so you could use it to calculate the weight of a pouch that could hold a given tension.
I can't find a decent supply of leather anywhere! It's so vexing!
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