HTV Silicone Rubber Processing / Extrusion Extrusion is the fabricating technique to produce continuous profile shapes such as tubing, rods, gaskets and seals. With this process and the use of a cooled extruder, the rubber is continuously pushed through a die that forms it to the desired cross-sectional size and shape. Hot Air Vulcanization (HAV) is the most used method of making tubing and profiles. HAV consists of a heated tunnel of 10-15 meter length through which the tube or profile is fed continuously on a moving conveyor. Air temperature reaches 250 to 350 degrees C. Vulcanization in a salt bath is also possible. After extrusion process the parts, especially those for intended use in the food and health-care industry must be post-cured which takes place in an oven for at least 4 hours at 200 degrees C to remove volatiles and curing agent decomposition by-products. Enough fresh air circulation must be present during this process. Traditional curing agents for silicone rubber compounds are organic peroxides which, when heated, decompose to form free radicals that react with the organic groups on the silicone polymer. An alternative method is the addition cure system by using a platinum catalyst. Curing agents, additives and pigments are usually added to the rubber compound on a two-roll mill.