THE ART AND SCIENCE OF ELASTOMERS
Built on real industrial experience, this masterclass bridges theory and production reality, offering insights that go beyond textbooks and into the core of rubber manufacturing.
Chapter 14
Liquid Silicone Rubber (LSR)
Some rubbers are rugged.
Some are soft.
But when an application demands purity, precision and perfection, the answer is LSR.
Liquid Silicone Rubber is the advanced evolution of silicone, engineered for speed, accuracy and absolute cleanliness. It shares the same siloxane backbone as solid VMQ, offering outstanding thermal and chemical resistance. But what sets LSR apart is how it’s processed.
It begins as a two-part liquid system: Part A and Part B, stored in separate containers. Pumped through a metering system, they’re mixed in a precise ratio and injected directly into a closed, heated mold.
No preforms.
No manual loading.
Just a clean, automated, fully enclosed process.
Inside the mold, the addition-cure chemistry, driven by a platinum catalyst, works fast. LSR crosslinks rapidly, often requiring little or no post-curing. And with minimal or no flash to remove, the part is ejected clean, finished and ready to use.
That precision makes LSR the material of choice for critical, flawless components.
You’ll find it in medical and healthcare products such as implants, baby-care items and respiratory devices. It’s also used in consumer technology, in wearables, hearing aids and electronic gaskets, as well as in optical and industrial applications like lighting seals, lenses and other high-purity systems.
LSR performs across extremes, from cryogenic lows near –60 °C to continuous service above 200 °C. It resists oxygen, ozone, sterilization processes and moisture. It doesn’t leach, outgas, stain or contaminate. Medical grades are certified for prolonged skin contact and even for use inside the human body.
But LSR isn’t perfect.
Its tear strength is generally lower than that of many other elastomers. It isn’t designed for abrasion or high-friction wear. Its platinum-catalyzed curing system is sensitive and can be inhibited by traces of sulfur, amines, organotin compounds or certain metals. And it requires specialized tooling and equipment, at a higher cost than traditional rubber molding.
Still, when manufacturing becomes micro-engineering, when precision, purity and repeatability matter above all else, LSR is unmatched.
