From homes, hospitals, automobiles, footwear and apparel, foams are a necessary part of a variety of products. But what is a foam? At its simplest, a foam is a compound formed when gas is trapped by a liquid or solid. Solid foams are naturally occurring, such as sea sponges, but can also be manufactured with both natural and synthetic raw materials. Foams are typically measured by density, or how stiff the foam is, as well as compression set resistance, or how quickly and easily the foam is able to bounce back after being compressed.
Synthetic foam uses:
- Home: insulation, mattresses, fireproofing
- Medical: gaskets, sealings, orthotics, dressings, device attachments
- Automotive: headliners, car seats, arm rests, door cladding, sound proofing
- Soft goods: footwear, padded athletic gear, backpack and bags, bras, swimwear, makeup sponges
Generally, foams are separated into two categories: open cell and closed cell. The gas molecules in open cell polyurethane (PU) foams are connected with one another, resulting in a textile that is spongier, softer, more flexible, and more comfortable than traditional closed cell foams. Open cell foams also tend to come in more colors than conventional synthetic foams. However, open cell foams are not as waterproof or durable as their closed cell counterparts. Because of the limitations of each of these types of foams, open cell foams are typically relegated toward being used onto specific places like on shoe uppers, and conventional closed cell foams are typically only utilized in places like the midsole, adding supply chain steps to the manufacturing process.
Foams are used throughout the construction of nearly every shoe on the market. Synthetic and natural foam materials are typically found lining the footbed, in the midsole, tongue, collar, uppers, in any ankle or stability features, in tread to increase grip, backing fabric to set stitching and reduce wrinkles. Because the raw materials can be blended in different ratios, the resulting material can vary widely in terms of density, compression set ratio, elasticity, and breathability.
Common types of natural and synthetic foams:
- Polyethylene: PE is typically pressed out into sheets, dye cut, and laminated; waterproof
- Latex rubber foam: hasn’t been vulcanized; can be used for soles and combined with synthetic raw materials for a hybrid product
- Memory foam: originally developed by NASA, memory (also known as temper foam) is made primarily of polyurethane, and has very slow “springback” that is characteristically found in mattresses and in medical settings; can be open or closed cell
- Ethylene vinyl acetate: EVA is the most commonly used material in footwear, commonly found in midsoles. It’s a copolymer that can have differing ratios of vinyl acetate and ethylene, resulting in a material of varied quality and durability
- Neoprene: Also known as polychloroprene; can be manufactured from rubber or latex, and found in laptop sleeves, wetsuits, and braces. It’s highly resistant to degradation, making it a good choice for lining landfills but tends to be harmful to the environment when utilized for footwear and apparel
- Styrene butadiene rubber: typically found in the soles of shoes SBRs good abrasion resistance with the addition of protective additives
- Ariaprene: a highly customizable and moldable closed cell TPE material that can be layered for soft touch qualities similar to open cell PU. Generally found between 1–15mm in thickness, and 8-30C hardness, and available in a high stretch series, low heat-shrinkage series, and shock-absorbing series. Requires less energy during manufacturing and is degradable and recyclable, unlike most footwear textiles.
There have been recent motions from several footwear and apparel industry giants to increase the use of synthetic materials over their traditional natural counterparts, like leather or latex rubber, which require materials from animals, or can cause serious allergic reactions, respectively. High performance synthetic foams have consistently proven to be more eco-friendly, more affordable, reliable, safer to designers, manufacturers, and end users. And unlike conventional synthetic foams, Ariaprene’s custom foam core packages allows for more design possibilities, colors, combinations thanks to Tiong Liong’s proprietary manufacturing process.