Post actualizado el día octubre 25, 2026 by DeiviSanzPlay
Silicone is in your kitchen, in your bathroom sealant, in the phone you’re holding and even inside your body if you have an implant. It’s one of those materials that nobody values until it fails. And when it fails, you’ve got a mess on your hands: a poorly chosen gasket and you have a leak; the wrong silicone mold and your food sticks to it or it warps with the heat.
So let’s get down to practical matters. Here are the types of silicone that exist, what each one is used for and which one suits you depending on what you need. No beating around the bush.
What silicone is and why it withstands what other materials can’t
Silicone is a synthetic polymer made from silicon, oxygen and organic groups such as methyl. Its backbone is a silicon-oxygen chain (siloxane), and that gives it brutal thermal stability: it withstands from -50 °C to over 200 °C without breaking a sweat.
That’s why silicone is used as a sealant in construction, in oven utensils, in breast implants, in prosthetics, in electrical cables and even in intimate lubricants. Its flexibility, its water resistance and its electrical insulation capacity make it irreplaceable in many niches.
A fact many people don’t know: silicone is not the same as natural rubber or plastic. Rubber degrades with sun and ozone; silicone resists UV, ozone and many acids. That said, not all types of silicone are the same, and that’s where the confusion lies.
RTV silicone: the queen of DIY and sealants
RTV (Room Temperature Vulcanizing) silicones are the ones that cure at room temperature. You surely know them: that tube of sealant you apply with a caulking gun and the next day it’s like a flexible stone. They’re used to seal windows, bathrooms, engine gaskets and also to make homemade molds.
Within RTVs there are two families that you shouldn’t confuse: acetic-cure (they smell like vinegar, don’t use them in electronics because acetic acid corrodes) and neutral-cure (odorless, suitable for metals and circuits). If you’re going to seal a circuit board or an electronic component, always go for the neutral one.
Its strong point is ease of use. Its weak point: they’re not designed for mass production or high mechanical stress.
LSR silicone: the strongest and the one factories use
LSR (Liquid Silicone Rubber) silicone is liquid rubber silicone, and it’s the answer to the question «which is the strongest silicone». It’s injected into molds and cures with heat, which allows manufacturing parts with millimetric precision and in large quantities.
Here’s the key to its strength: fillers such as fiberglass can be added to improve mechanical resistance. That makes it ideal for automotive components, engine seals, diving masks, baby bottle nipples and medical devices that must withstand repeated sterilizations.
If you need silicone for a demanding application, LSR is the industrial standard. It’s not cheap, but it lasts.
Types of silicone by grade: food-grade, medical-grade and more
This is where people make the most mistakes. Buying sealant silicone to make a chocolate mold is reckless. These are the grades that matter:
- Food-grade silicone: certified for food contact (FDA or equivalents). It’s used in baking molds, spatulas, baby bottles and container lids. It doesn’t release toxins at normal oven temperatures (up to 220-230 °C).
- Medical-grade silicone: higher purity, biocompatible and hypoallergenic. It’s used in implants, catheters, prosthetics and dressings. It complies with standards such as USP Class VI or ISO 10993.
- Adhesive silicone: formulated to stick without the need for sealing. It’s used in tapes, patches and temporary fixings.
- Silicone foam: with cushioning properties. It’s used in thermal insulation, pads and seals that need compressibility.
A street-smart tip: if a product doesn’t specify the grade, assume it’s not suitable for food contact or medical use. Don’t play around with that.
What silicone is used for in everyday life (and in industry)
In the kitchen you find it in molds, spatulas and oven mats. In the bathroom, in anti-mold sealants. In electronics, insulating cables and protecting sensitive components. In medicine, in implants and devices. In cosmetics, in shampoos and makeup to improve texture and application.
Silicone is also in the automotive industry: hoses, gaskets, headlight seals. And in construction: sealing expansion joints, glazing and bathrooms. Its weather resistance makes it perfect for outdoors.
That said, not everything goes. An acidic silicone on an aluminum frame can eat away at it over time. And a technical-grade silicone in a food mold is a bad idea. Each use has its type.
How silicone is manufactured: from grains of sand to polymer
It all starts with silica (silicon dioxide), which comes basically from sand. That silica is purified and reacted with carbon at high temperatures to obtain metallurgical silicon. Then, that silicon is combined with methyl chloride to form chlorosilanes.
Through distillation and hydrolysis, the chlorosilanes are transformed into siloxanes, and the most common is polydimethylsiloxane (PDMS). That PDMS is the base of most silicones you see on the market.
From there, fillers (silica, fiberglass, pigments) and catalysts are added to give it its final properties. Curing can be by heat, by moisture or at room temperature. That step determines whether the silicone will be soft, hard, transparent, resistant or flexible.
Which one to choose based on what you need (quick guide)
If you’re going to seal a joint at home, neutral RTV. If you’re going to make molds for crafts, RTV silicone specifically for molds. If you’re going to cook, food-grade. If it’s for an implant or medical device, medical-grade and certified. If you need resistant industrial parts, LSR.
And watch out for temperatures: not all silicones withstand the same. Some resist up to 300 °C in short peaks, but continuous use above 200 °C shortens their life. If your application is sustained high temperature, look for silicones formulated for it, not the generic one from the bargain store.
Silicone is not a single material: it’s a family. Choosing the right type saves you money, headaches and, in medical or food applications, serious problems.
