Silicone grease is everywhere, yet rarely noticed. From the watertight seal of a smartphone to the vacuum-tight joint of a satellite,this translucent paste keeps modern industry alive. 

The following article dissects what silicone grease is, where it excels, where it falters, and how to match the right grade to your engineering challenge.

1. What Exactly Is Silicone Grease? 

Chemically, silicone grease is a semi-solid lubricant composed of three building blocks: 

- Base fluid: polydimethylsiloxane (PDMS) oil –50 °C ➜ +200 °C (specialty grades up to 300 °C) 

- Thixotropic filler: amorphous silica (≈ 5–15 wt %) that turns oil into a non-flowing paste 

- Performance additives: anti-oxidants, corrosion inhibitors, colourants, vacuum-proofing agents 

The result is a colourless-to-white, non-curing, non-melting compound that combines the temperature stability of silicones with the gap-filling ability of a grease.

2. Strengths & Limitations at a Glance 

Strengths 

✓ Wide temperature window –50 °C to +200 °C (300 °C for phenyl-modified grades) 

✓ Chemically inert—resists water, ozone, UV, brine and most industrial gases 

✓ Excellent dielectric properties: volume resistivity > 1×10¹⁴ Ω·cm, εr ≈ 3–4 @ 1 kHz 

✓ Low vapour pressure (<10⁻⁶ mbar) for high-vacuum use 

Limitations 

✗ Poor load-bearing capacity—unsuitable for engine crankshaft or heavily-loaded steel gears 

✗ Can swell natural rubber or stress-crack certain plastics (ABS, PC) if not compatibility-tested 

✗ Price premium 3–5× versus mineral-oil greases, which matters in high-volume, low-margin goods

3. Three Mission-Critical Application Arenas 

A. Sealing & Waterproofing – “Moisture Armour” for Precision Hardware 

Function: fills micro-gaps, blocks liquid water and water vapour, while still allowing parts to be disassembled. 

Typical uses: O-rings on underwater camera housings, automotive electrical connectors, potable-water faucet cartridges (NSF-61 grades).

B. High-Vacuum Grease – The Space-Qualified Lubricant 

Function: lubricates and seals without contaminating optical elements or semiconductor wafers. 

Typical uses: vacuum chamber quick-seals (ISO-KF), space-qualified optical barrel threads, synchrotron beam-lines. 

Key specification: TML (total mass loss) <1 %, CVCM (collected volatile condensable material) <0.1 % per ASTM E595.

C. Electrical-Insulating Grease – Dielectric Safety Barrier 

Function: prevents tracking, arcing and humidity-induced failures on live parts. 

Typical uses: high-voltage insulator bushings, spark-plug boots, battery pack terminals of EVs, overhead-line disconnect switches.

4. Key Take-away 

Silicone grease is not a generic commodity; it is an engineered solution. 

Match the chemistry to the stressor—temperature, vacuum, voltage, media, regulation—and the invisible paste becomes the most reliable component in your assemblIf you have any needs, please feel free to contact us at any time. Our professional team will provide you with the most suitable products.