Material Matters: Latex Rubber
It’s been used to make everything from surgical gloves, washing machine gaskets, and even chewing gum! However, one of the most important applications of latex rubber has been to make sneaker components. This latest instalment of Material Matters explores exactly how the stretchy compound has been saving our soles for hundreds of years.
A Brief History of Latex Rubber
Latex refers to a number of different materials that have elastic properties – i.e. they spontaneously try to return to their original state upon being stretched or compressed. With that definition in mind, you can easily see how latex is so useful for sneakers.
We’ve visited vulcanised rubber in an earlier edition of Material Matters, but the abridged version of rubber history is as follows. South America’s Olmec people were cultivating latex from hevea brasiliensis, or the rubber tree, as early as 1600BCE. However, its appearance in Western society wasn’t prominent until the 1750s, when the French and English analysed it scientifically.
Then, in 1844, Thomas Hancock submitted a patent for vulcanised rubber, eight weeks before the historically more well-known Charles Goodyear submitted his Stateside. Get the full story here. Once vulcanisation was perfected, it would prove to be one of the most effective ways of constructing sneaker soles due to its simplicity, strength, durability, and many other benefits.
In general terms, latex refers to rubber that hasn’t been vulcanised. It can be split into two categories: natural and synthetic. The natural version is championed by New York–Sydney brand FEIT, such that they focus an entire range around the material. The small-scale shoemakers work with Lactae Hevea, a company that harvests natural latex from hevea brasiliensis. FEIT's Biotrainer silhouette uses latex soles, which feature siping for flexibility.
French label VEJA is known for their Brazillian-made, ecological sneakers that use materials sourced directly from the Amazon rainforest. One of these materials is natural latex which is blended with a synthetic variety to form a hybrid latex for the brand’s soles.
Natural latex milk or sap collected directly from its source can be used as glue too!
Latex is still a widely-used traditional material for footbeds. Birkenstock’s ergonomic footbeds are made from a mix of cork and latex foam, as it’s a breathable yet structured combination.
Latex is also commonly used today as foam in mattresses and pillows. In foam form, latex is highly breathable and retains its elastic properties. This makes it useful for insoles, as its elasticity stops the insole from bottoming out too quickly from prolonged wear. In the 80s and 90s, many basketball shoes had latex foam arch support inserts attached to the insoles. Latex can also be mixed into other foams because of its relatively light weight, such as VEJA's L Foam cushioning.
Adding extra latex foam insoles to sneakers is a quick solution for those who need to adjust their fit ever so slightly. They can be cut to size, usually with a template printed on the exposed foam side, and are available at supermarkets and chemists worldwide.
Latex can also be used for aesthetic purposes. Viscous forms of liquid latex can be applied to the surface of sneakers for a ‘drip’ effect once dry. This effect has been somewhat popular in recent years within the custom sneaker scene.
Parts of the population exhibit allergic reactions to natural latex because of certain proteins contained in it. While most of these reactions involve skin irritation or rashes, a small proportion of people may experience anaphylaxis when they come into contact with latex. As a result, synthetic latex is favoured in some applications where there is a lot of contact against the skin. For example, some latex insoles are made hypoallergenic to avoid any adverse reactions.
Nike uses Synthetic Latex in most footwear, which is hypoallergenic because it is protein free. We cannot guarantee that our shoes are 100% Latex free. While we do not include or use Natural Latex in the manufacture of footwear, trace Latex properties may exist.— Nike (@Nike) May 24, 2018
Is There a Future in Latex?
Definitely! Recycled and organic materials have recently made a resurgence in many smaller, independent vegan shoe brands that choose natural latex for their soles. However, latex in its various synthetic forms seems to be the way forward for many brands due to its stability and durability. Nike have stated on Twitter that most of their footwear uses synthetic latex for its hypoallergenic properties.
Given that almost 14 million tonnes of natural rubber was produced in 2018, latex is likely going to remain a part of our sneakers for many years, if not decades, to come. The next challenge for footwear brands is to continue innovating in new and creative ways with a natural resource that has existed for thousands of years. The big brands are stepping up their eco game, but it remains to be seen what the ‘Next Big Thing’ will be. Do you think it will involve latex?