Vinylal/Vinylon F

Vinylal is an artificial fabric used, for example, in the production of backpacks. Despite its synthetic origin, it behaves like a natural fiber.

The advantage of vinylal (which, for example, the Swedish company Fjällräven calls by its trade name Vinylon F) is the minimized need for impregnation. Once this fiber gets wet (for example, in the rain), it swells, paradoxically making it stronger.

This fabric is defined as "a fiber made from linear macromolecules with a chain composed of polyvinyl alcohol with varying degrees of acetylation." It sounds quite complex, and you are right, vinylal is not produced by a particularly simple process. This material (or class of materials) was invented back in the 1930s in Japan, which today remains the second largest producer after China.

Polyvinyl alcohol fibers, produced by a process called wet spinning, are divided into soluble and insoluble fibers. Only the soluble ones are used for the production of textiles (including household textiles). The insoluble ones can be used to make, for example, ropes and nets, or composites reinforcements for the construction industry.

The advantages of vinylal, besides its good impregnation properties, also include its decent resistance to ultraviolet (UV) radiation, which commonly degrades other materials, and chemicals. Vinylal materials also have high abrasion resistance. That's why companies like Fjällräven use them for their outdoor products. For example, the iconic Kånken backpack has been made from vinylal since 1978.

Interestingly, per capita, the largest producer of vinylon (referred to locally as vinalon) is likely North Korea, where some "Western" clothing (such as jeans) is banned, and instead, certain "uniforms" made from vinylon are used.