Personally I think the vulcanizing shoe making process is one of the most fascinating processes in the shoe business that you hear very little about. There is so much science and planing involved with it and it’s something that blows me away every time I see it.
Vulcanizing is a process in which you are literally cooking your shoes in an oven until they’re finished. When I think vulcanized shoes brands such as Vans and Converse come to mind immediately.
There are a few key components that are critical to this process in order for the process to be effective
Last: #lastcomesfirst which are made of aluminum because traditional resin Last would melt and catch fire in the chamber.
Vulcanized chamber: this is the oven like machine that the shoes are placed in after they have been assembled were temperatures can exceed 150 degrees fahrenheit.
Materials: it’s critical that the materials used on vulcanized shoes can withstand high temperatures in the chamber. Materials such as canvas, leather, and metal eyelets are commonly used in styles like the Chuck Taylor or Old Skool and you never see materials like silicon, EVA, plastic, or PU leather (fake leather) used because these materials are considered flammable and can melt or catch fire while in the chamber.
After the patterns are cut, stitched and lasted using a combination of the materials (listed above) the sole is then constructed starting with a thick rubber outsole, and finished with a rubber foxing tape that wraps 360 degrees around the base of the shoe. The rubber sole and foxing tape are lightly cemented so they are held in place and once all the shoes are ready they are placed on a steel rack that can be wheeled into the chamber. Once inside the chamber the vault like door is air locked and the machine is turned on. As the temperature increases inside the rubber sole, foxing and upper material starts to bond to each other creating a tight seal and forms that “vacuum sealed” look you get on the side of the sole. After 30 mins or so of “cooking” the racks are removed so the shoes can cool off before they are un-lasted and this entire process is repeated again.
Generally this is a rather inexpensive way to make shoes, however the catch is the MOQ’s (minimum order quantities) are very high, in excess of 3000 to 5000 pairs per color, which is why you only see a few brands that actually do it. The set up cost is expensive because of the aluminum last that are required and generally have high MOQ’s themselves. It’s a great process that’s very fascinating but was specifically designed for high volume mass production.
It would be a great process to see taken down on a smaller scale and really see how designers could push this process and do some fun things with it. There are a few examples of brands that have done this but seeing this available to independent designers and makers could be a lot of fun…maybe my NY based factory, “The Kicks Factory” will have something to say about that sooner rather later. Stay tuned.
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