How silicone is made

Silicone is a chain of silicon and oxygen atoms dressed in carbon groups, and it is made from sand.

stations: 6
things upstream: 17
raw sources: 9
steps from the ground: 4

The short version

Silicone is made from metallurgical silicon, which is ground and reacted with methyl chloride to form chlorosilanes. These liquids are distilled apart and mixed with water, which links them into silicon-oxygen chains. Chain length decides whether the product is an oil, a grease, a rubber or a resin, and fillers and curing finish the job.

Start from silicon metal

Metallurgical silicon, smelted from quartz sand, is ground to a fine powder. The fine grains give the next reaction plenty of surface.

Goes in
Metallurgical silicon
React it with methyl chloride

In a fluidized bed, the silicon powder is lifted on a stream of methyl chloride gas with a copper catalyst. The result is a mix of methylchlorosilane liquids, with dimethyldichlorosilane the main one. Methyl chloride is made commercially from methanol and hydrochloric acid.

Goes in
Methanol Hydrochloric acid
Distill the chlorosilanes

Tall columns separate the near-identical liquids by their boiling points. Purity at this stage decides how long the chains can grow.
Hydrolyze with water

The purified liquid meets water, and hydrochloric acid is released. What is left forms silicon-oxygen rings and short chains, called siloxanes.

Goes in
Water
Grow the chains

Catalysts link the siloxanes into long chains. Short chains make oils and long chains make gums, and the length is set to match the product.
Fill and cure into rubber

For rubber, the gum is worked with fine silica filler and a curing agent, then molded or extruded and heated. The chains cross-link into a flexible solid that stays soft in the cold and the heat.

Goes in
Silica sand

End of the lineSilicone Next it goes into shampoo, deodorant, syringe and 14 more.

Worth repeating

Frederic Kipping coined the word silicone in 1901 and is called the father of silicones, credited with launching the industry in the 1930s.
Silicones have an inorganic backbone of silicon and oxygen but behave like organic polymers.