What soles are made of: Your guide to footwear tech lingo

- Jul 12, 2019-

Here’s our guide to today’s footwear tech lingo for your inner scientist — whether you’re working the sales floor or updating inventory for next season.

The more technical outdoor footwear gets, the more its product descriptions resemble alphabet soup. PVC, EVA, PU, TPU ... what’s the difference?

Even leather, the figurehead of the hiking boot industry, comes with its own set of jargon. The "top grain” is the tighter, tougher external surface of the animal’s skin. Roughing up the top grain will produce abrasion-resistant Nubuck, while taking the sander to the inside of the hide yields suede, Nubuck’s cheaper, stretchier, more absorbent cousin. Leather is breathable, develops softness and character over time, and has a classic look many customers prefer, but comparatively cheap, low-maintenance synthetics draw many buyers away.

Polyurethane (PU) is one of the most common polymers used in shoes, and for good reason — it’s lightweight, durable, and waterproof. PU is also remarkably oil-resistant, which makes it a great ingredient in boots designed for construction or industrial use. 

Thermoplastic polyurethane (TPU) is a subset of PU. TPU can be re-melted and remolded even after it’s solidified, which makes it easier to work with and opens up an array of processing possibilities.