HTV and RTV Silicone Rubber: Classification by Cure Method
The most common way to classify silicone rubber is by how it cures: HTV (high temperature vulcanized, also called heat-cured) and RTV (room temperature vulcanized). The two types differ in molecular weight, physical form and processing, and so in their applications.
HTV: high temperature vulcanized
HTV is a high molecular weight, semi-solid gum that looks like modeling clay and is processed much like ordinary rubber. To shape it, the compound must be heated to around 160°C and placed in a mold to obtain accurate form and dimensions, which is why HTV is also called molded silicone. Typical products are silicone keypads, silicone rubber seals and sleeves.
RTV: room temperature vulcanized
RTV is a low molecular weight liquid that cures at ordinary temperature. Curing begins once it is exposed to air and runs entirely at room temperature, with no added heat and no mold. Typical RTV products include flexible adhesives, silicone bonding agents, thermally conductive adhesives and potting compounds.
Choosing between them
| HTV | RTV | |
|---|---|---|
| Form | Semi-solid gum | Liquid |
| Cure conditions | About 160°C, mold required | Room temperature, no mold |
| Typical uses | Keypads, seals, sleeves | Bonding, potting, sealing |
For molded parts that must be made in volume to precise dimensions, choose HTV. For applications done on site, such as coating, bonding or potting, where heat and pressure are not practical, choose RTV.