The bend test
A German materials testing institute called FILK Freiberg bent 1 sample of real leather and 9 materials sold as alternatives to it, all on the same bending machine, called a flexometer, under the same international testing standard, ISO 32100. The machine folds a material back and forth and counts how many folds it takes before the surface cracks. The shoe leather industry standard, ISO 20942, requires a material to survive at least 80,000 folds before it counts as durable enough for shoes, gloves and bags. Leather kept folding past 200,000 times, and the institute stopped the test rather than wait for it to crack. Only 2 of the 9 alternatives matched that bar, a textile coated in polyurethane plastic, which held for 200,000 folds, and Pinatex, made from pineapple leaf fiber, which held for 150,000. Every other alternative fell short, some badly. Cactus based Desserto reached 30,000 folds, apple waste based Appleskin and grape based Vegea each reached 50,000, mushroom based Muskin and a fermented material called Kombucha each reached only 10,000, and a coated teak leaf material cracked after just 100 folds.
Leather and the polyurethane coated textile had not cracked when the test stopped at 200,000 cycles. The shoe leather industry threshold, ISO 20942, is 80,000 cycles. Teak Leaf, the shortest lived material tested, reached only 100 cycles and is not shown on this scale.
Show the numbers
| Leather | 200 |
| Polyurethane coated textile | 200 |
| Pinatex | 150 |
| Appleskin | 50 |
| Vegea | 50 |
| Desserto | 30 |
| Muskin | 10 |
| Kombucha | 10 |
| SnapPap | 5 |
One material stands out
Pinatex is the only plant based material in the test that came close to leather. Its maker, a company called Ananas Anam, has also run a separate wear test called Martindale, which rubs a material in small circles to measure how the surface holds up rather than how many times it can bend. Two outside accredited labs ran this test across 6 Pinatex product lines. The toughest line, called Light Midrib, showed no breakdown after 300,000 rubs. The weakest tested line, Light Velvet, started to break down after 100,000 rubs. This is a different test on different product versions, so it does not sit on the same scale as the bend test above, but it points the same direction, Pinatex holds up.
Original, Mineral, Metallic and Performance are the highest cycle count each passed with no breakdown recorded, testing did not continue further. Light Velvet is the only line where breakdown was recorded starting, at the cycle count shown.
Show the numbers
| Original and Mineral | 50 |
| Metallic | 50 |
| Performance | 50 |
| Light Midrib | 300 |
| Light Velvet | 100 |
Not yet tested for a car
None of this covers a car seat. The Freiberg Institute states plainly that it left automotive and upholstery materials out of its comparison, because cars demand a higher specification than shoes, gloves and bags do. That gap already shows up on the road. The mushroom based leather fitted into the interior of the Mercedes Vision EQXX concept car came from a material called Mylo, made by Bolt Threads. The company halted Mylo production in July 2023, after raising more than 300 million dollars and running 2 rounds of layoffs, unable to reach the scale a car factory needs.
We are not immune to the same macroeconomic pressures everyone else is facing, so we have paused Mylo to reassess what works and what will work in the future.
Dan Widmaier, Chief Executive Officer of Bolt Threads. Source 4.
Cadillac and the material company MycoWorks announced a new collaboration on a similar mushroom based material, called Fine Mycelium, in June 2024. So far it has produced 1 built object, a card holder, attached to SOLLEI, an all electric concept convertible Cadillac unveiled the following month. Neither company has published a wear test for the material inside a car.