The shoe assembly process that appliers rubber in it’s “raw” or uncured state to the shoes lasted upper. The upper and rubber parts are treated with gull before assembly. Once the assembly is complete the entire shoe (with the aluminum last still inside) is placed inside a steam heated Autoclave or vulcanizing oven. After heating the rubber is now vulcanized. Uppers must be made from heat resistant materials, commonly canvas or suede leather. The Classic Converse All-star and Vans slip-on shoes are vulcanized shoes.