For the past five years, adidas’ BOOST foam has been on top and we’ve been waiting to see what Nike’s response would be for just as long. We can’t begin to guess the timeframe that the Swoosh work on, but many would posture that no matter how good Nike’s new React foam may be, it’s too late. On the other hand, Nike have had years of R&D to perfect the formula that may topple the adidas tech — an eternity in the lifespan of a sneaker. So, aesthetics aside, what are the chances that Nike’s React Foam could mark the end of the BOOST era?
From an observer’s point of view, foam is foam, right? You wouldn’t think there could be all that much separating one kind from another, but you’d best believe there is some serious chemistry going on to produce the soft stuff.
The earliest form of foamed rubber came in 1929 when a chemist named Eric Owen simply whipped up some latex, as if he was whipping cream for his scones. Enter the science of polymeric foam — that is, foam made using polymers like plastic and rubber.
The first foam to make its way onto a sneaker was EVA, a mixture of two polymers: ethylene and vinyl acetate. It’s been the industry standard for well over 30 years. From the very early days of the material’s use, shoe manufacturers have explored the benefits of changing the ratios of ingredients. And more recently, the process by which the raw materials are combined, expanded (foamed), and moulded. There are variations in mixing, moulding, heating and cooling that all result in a product with slightly different properties.
Everything can be tweaked, including density, springiness, durability, ageing and reaction to ambient temperatures — and that’s only one kind of foam. Nowadays, brands also have the choice of using TPU (thermo-plastic polyurethane), which is subject to the same amount of variation, if not more.
Prior to the release of React, Nike’s top-tier foam was Lunarlon, made from EVA. Lunarlon is super lightweight, but it doesn’t measure up in springiness to BOOST, which is made from TPU. To make matters worse for TPU, its predecessor, PU, was shunned by the industry in the 90s. PU was used in a lot of soles because it was so easy to mould and worked well to stabilise softer EVA components. It’s used for the shell of New Balance’s ENCAP soles and housed Nike’s Air units. But, as anyone who’s ever dabbled in vintage footwear will know, PU doesn’t tend to endure.
With that in mind, it makes sense that sneaker brands focussed most of their effort on EVA — until recently its downsides were unavoidable. The foremost of which being that EVA is not particularly durable against abrasion and it has poor compression set. Basically, over time it loses its spring. Clearly, the old-school foam was no longer the way forward, and then came the new kid on the block. German chemical manufacturer BASF discovered the breakthrough for TPU, when they created micro pre-expanded TPU. This obviously points towards a key downside for BOOST, as opposed to React. Where React is a proprietary technology that belongs to Nike, adidas don’t actually own the patents to their top-tier sole tech.
What Nike’s team of in-house chemical scientists have cooked up is an entirely new synthetic rubber. Of course, being Nike, they haven’t revealed much about what it’s actually made from. What we do know is that it uses new ingredients and takes advantage of modern fluid geometry. They tested the new Epic React Flyknit against their previous top running style, the LunarEpic Flyknit 2 and found it to be significantly softer and springier, as well as a whole lot more durable. Then, just to add a little extra kick, they announced that React is 30 per cent lighter than BOOST.
The other major consideration is that as good as BOOST is for making shoe soles, it wasn’t actually designed for that specific purpose. BOOST was created in a lab at BASF, followed by a ‘what can we do with this?’ type of conversation. Nike’s React foam, on the other hand, was created in collaboration with their athletes, meaning that throughout the process they were able to tweak the formula to optimise performance.
In the end, however, there will probably never be a perfect mass-market foam. The problem is, the more fine-tuning that goes into the performance of the foam, the more specific the ideal wearer becomes. For instance, the weight and running speed of an athlete will massively alter the experience of compression and energy return. The challenge is to find the perfect balance of all factors involved.
Although the real-world success of Nike’s new tech remains to be seen, in the matter of React versus BOOST, the chips are really stacking up on the side of the Swoosh. Furthermore, the adidas tech has remained more or less unchanged for the past five years. For adidas to say the sole they released in 2013 is still ‘the best you can get’ is like Apple telling you that the iPhone 5S is still a cutting-edge smartphone.
It’s about time for something new and it looks like Nike’s new hero foam may be just the thing.
Material Matters is our weekly tech section where we peek behind the mesh curtain and examine the building blocks of the industry. Recently, we’ve looked at How Nylon Changed the (Sneaker) World, The Weird and Whacky Sneakers of Today and Why Shoe Sizes Don't Make Sense.