About one hundred and twenty years earlier, Jones Jacob Berzelius produces first condensation polymer, polyester, from glycerin and tartaric acid. He is also credited with originating the chemical terms "catalysis," "polymer," "isomer," and "allotrope," although his original definitions differ dramatically from modern usage. From the metering section of the injection molding machine, the compound is pushed through cooled spruce and runner systems into a heated cavity where the vulcanization takes place. The cooling allows production of LSR parts with nearly zero material waste, eliminating trimming operations and yielding seal tags.

Because of their viscous nature, these liquids are pumped at high pressures based on the udometers of the material. The raw materials are shipped in two separate containers identified as "A" and B" compounds, with the "B" side usually containing the seal tags, but may vary based on the brand of silicone used. The two compounds must be mixed in a 1 to 1 ratio, usually by way of a static mixer. Once the two components come together the curing process begins immediately. A chiller supplying cold water to jacketed fittings is typically used to retard the curing process prior to the materials introduction to the mold. A color pigment can be added via a color injector used in conjunction with the material pump before the material enters the static mixer section.

In a cold deck scenario, the 1 to 1 mixed compound is pumped through cooled spruce and runner systems into a heated cavity where the vulcanization takes place. The cold runner and general cooling results in minimal loss of material as the injection occurs directly into the part or cavity. The cooling allows production of seal tags with nearly zero material valve gate waste; however this does not guarantee a "flash free" finished part. Molds and tooling are varying in design, execution and cost. A good cold runner is expensive as compared to conventional hot runner tooling, and has the potential to provide a high level of performance.