Views: 0 Author: Site Editor Publish Time: 2026-04-10 Origin: Site
If you've ever shopped for silicone products — whether it's a baby bottle nipple, a kitchen spatula, or a smartphone case — you probably assumed all silicone is the same. It's not.
In fact, there's a fundamental divide in how silicone rubber parts are made: Liquid Silicone Rubber (LSR) vs. High-Temperature Vulcanizate (HTV) , also known as solid silicone rubber.
While both materials are silicone, their manufacturing processes — and therefore their costs, quality, and applications — are worlds apart.
Here's a no-nonsense guide to help you understand the difference.
LSR behaves like a liquid. It's injected into hot molds automatically, creating high-precision parts with no waste. Think: mass production, tight tolerances, complex shapes.
Solid silicone (HTV) behaves like bread dough. It's manually weighed, placed into a mold, and pressed under heat. Think: small batches, simple parts, lower startup cost.
Feature | LSR Injection Molding | Solid Silicone (HTV) Molding |
|---|---|---|
Material Form | Liquid (like honey) | Solid (like dough/clay) |
Process | Fully automatic injection | Mostly manual compression molding |
Cycle Time | Very fast (10–60 seconds) | Slow (minutes + trimming time) |
Precision | High (±0.01mm) | Moderate |
Waste | Nearly zero (cold runner) | Significant (flash/trimming) |
Tooling Cost | High (2–3x solid molds) | Low |
Best for | High-volume, complex, medical/food grade | Low-volume, simple shapes, budget starts |
LSR is the star of modern silicone manufacturing. The process looks a lot like plastic injection molding:
Two liquid components (A and B) are automatically mixed inside the machine.
The mixture is injected directly into a heated mold through a cold runner system — a clever design that keeps material in the runner liquid while the part cures.
In seconds, the part is fully cured, dimensionally perfect, and ready to use — no trimming, no flash.
Why manufacturers love LSR:
Zero waste — cold runners mean every drop of material becomes a product.
Unmatched consistency — perfect for medical devices, automotive seals, and baby products.
Overmolding capability — LSR can bond directly to plastic or metal in a single step (e.g., waterproof phone gaskets).
The catch: LSR molds are expensive. A single cold-runner mold can cost 2–3 times more than a solid silicone mold. You need volume — typically 10,000+ parts — to make it economical.
Solid silicone molding is simpler — almost primitive by comparison. Here's how it works:
An operator mixes raw silicone gum with a curing agent on a two-roll mill (like kneading dough).
They cut the material into precise weight pieces.
Each piece is placed into a heated mold cavity.
A compression press applies heat and pressure for several minutes.
After demolding, an operator trims off the excess flash by hand.
Why solid silicone still exists:
Low barrier to entry — basic compression presses are cheap. Molds are simple and affordable.
Flexible for small runs — perfect for prototypes or batches of a few hundred pieces.
Works with ultra-soft materials — some very low-durometer (soft) silicones don't flow well as liquids.
The drawbacks: It's slow, labor-intensive, and inconsistent. One operator might place the charge slightly off-center, creating a thick spot. Flash removal adds time and creates waste.
✅ Your annual volume exceeds 10,000–20,000 parts
✅ You need tight tolerances (±0.1mm or better)
✅ The part has thin walls, undercuts, or complex geometry
✅ You require medical, food-grade, or optical clarity
✅ You plan to overmold onto plastic or metal inserts
✅ Labor costs are high and automation pays off quickly
✅ You're making a few hundred or thousand parts for testing
✅ The shape is simple (gaskets, blocks, thick-walled parts)
✅ Your budget for tooling is under $1,000–2,000
✅ You don't mind manual trimming and some variation
✅ You need an extremely soft material (below 30 Shore A)
Holding a finished silicone part? Here's how to guess which process made it:
Look for a gate mark — LSR parts usually have a tiny, clean injection point. Solid parts don't have a gate but often show rough trim lines or irregular edges from flash removal.
Smell it — LSR is virtually odorless. Some solid silicones have a distinct sweet or rubbery scent from their curing agents.
Check clarity — High-transparency parts (like clear kitchenware) are almost always LSR. Solid silicone tends to look slightly hazy or milky.
Neither process is "better" — they serve different needs.
LSR is the future for anyone serious about quality, volume, and efficiency. It's the reason we can mass-produce medical seals, baby bottle nipples, and phone cases with incredible precision at low per-part costs.
Solid silicone remains a workhorse for small shops, prototypes, and simple parts. It won't win any speed or precision awards, but it gets the job done when volume doesn't justify an LSR mold.
If you're sourcing silicone parts, don't just ask for a quote. Ask your manufacturer: "Is this better suited for LSR or solid silicone?" The answer might save you thousands of dollars — or a lot of headaches.
