By Rehan Iqbal
Did you know that the first shoe basically consisted of some flat, flexible material and a string to hold it in place? While basic and rudimentary, it was this style that saw the evolution of modern footwear. But even though today’s lineup of footwear offers incredible features and durable materials for the uppers, we can’t overlook the most essential part; the outsole. As the foundation of your shoe, the sole is responsible for keeping you and the ground apart while offering you a comfortable place to set your feet.
Thankfully, technology has made it possible to construct some of the most practical and functional outsoles with slight variances for different purposes. Unfortunately, this immense array of outsoles and styles also makes getting the right match for your job a nightmare. While shopping for the best footwear for standing all day, you no doubt encountered a myriad of sole classifications and abbreviations that left you more confused than before. There’s something along the lines of RB, EVA, MD; and what the heck does PU outsole even mean? We shed some brightness on the types of outsole classification as well as the characteristics that make them unique.
Rubber Sole (RB)
If your shoe is marked RB, this basically means that the outsole is made with either hot press molding, sub-natural or recycled rubber. To ensure that the rubber sole fits the surface, it is ground and shortened. The great thing about rubber for your sole is that you get unmatched wear resistance as well as greatly extended contraction stability. Of course, rubber has desirable qualities like being bendable and waterproof. With this type of outsole, you’ll be breaking in your standing shoes real fast. However, rubber tends to make your work shoes a bit heavy.
Polyurethane Bottoms (PU)
A great sole needs to be durable, comfortable and fit for purpose, not to mention very affordable. Polyurethane outsoles allow designers to achieve all these objectives. They are practical, waterproof, and have excellent long term mechanical properties. When it comes to jobs that require you to be on your feet for hours, PU soles are quite the popular choice. They offer excellent wear resistance, low density, superb shock absorption, decent slip resistance. All these features make PU soles a great option for your next purchase.
Technically referred to as Ethylene Vinyl Acetate, EVA is a commonly used material for sock liners, midsoles, outsoles and even entire shoes. Currently, EVA offers one of the best shock absorbing properties on the planet. This is why almost every major top line brand uses it on their shoes. Due to the combination of features like lightweight, incredible flexibility, elasticity and excellent coloring EVA is another winner for outsoles expecting heavy usage.
TRP refers to Thermoplastic Rubber that was patented back in 1975. This type is produced by molding and compounding rubber granules from solid raw materials. Commonly, some manufacturers use shredder old car tires for their outsole. While this option offers immense slip resistance and great shock absorption, it tends to compromise a bit on comfort. Definitely a great option for an outdoor adventure, but not so much when you’re standing all day on the job.
That’s right people; PVC is not just for making your water pipes. Boating of unmatched mechanical strength, Polyvinyl chloride offers your shoe incredible insulation properties. When it comes to PVC outsoles, they provide a synthetic alternative to leather and allow for more cost effective options. Thanks to PVC’s capacity to be molded into different shapes, there are plenty of styles to choose from. PVC makes standing on the job for hours bearable thanks to shock absorbance as well as additional support.
This is simply a newer, more improved form of Polyurethane materials. This modified version is famous for its environmentally friendly features as well as surprisingly low density. But don’t be fooled by the modest appearance, BPU is among one of the most thick skinned outsoles in the market. Thanks to the extra toughness, they are very resilient, offer great weather resistance too. A definite must have if you spend most of your time standing outside in the elements.
If we’re talking about modern outsoles, then we can’t wind up without giving the newest kid on the block a mention. Abbreviation for Acrylonitrile Butadiene Styrene, ABS Outsoles are gaining traction for their exciting characteristics. This type of plastic is tough, durable and does not contain any toxins whatsoever. On a side note, ABS is also tasteless; but I wouldn’t recommend licking it to confirm, just take my word for it. ABS outsoles are well known for their excellent overall performance, great impact strength, abrasion resistance, easy molding and incredible stability. You also get decent electrical properties as well as resistance to chemicals. However, ABS offers poor weather resistance and works dismally in an outdoor setting. Additionally, people who work in extremely hot areas will not be pleased with the low thermal deformation temperature on ABS soles.