Fumed Silica Grease Explained
Fumed silica grease is a high-performance non-soap grease: instead of a metal soap, the base oil is thickened with fumed silica — a very fine, high-surface-area form of silicon dioxide (SiO₂). The silica particles build a three-dimensional network that holds the oil without melting, so the grease does not drip or soften at high temperature. That makes it a go-to where soap greases fall short — extreme heat, aggressive chemicals and water. Here is how it works, where it fits, and a typical data sheet.
A grease with no soap and no melting point
Most greases are oil held in a metal-soap thickener (lithium, calcium, etc.), and they have a dropping point — a temperature at which the soap softens and the grease flows. Fumed silica grease works differently: the thickener is fumed silica, whose enormous surface area lets it gel the oil physically.
Because there is no soap to melt, the grease has no true dropping point — it stays consistent to the limit of its base oil, not its thickener. That single property is why it survives temperatures and chemistry that destroy soap greases. It sits alongside other non-soap thickeners like organoclay (bentonite) and polyurea.
“Fumed” refers to how the silica is made — flame hydrolysis produces ultra-fine particles with huge surface area. That surface area is what does the thickening.
Key properties
- Thermal stability — operates roughly −40 to +250 °C without melting or dripping.
- Chemical inertness — resists acids, alkalis and most chemicals; ideal for aggressive environments.
- Water resistance — hydrophobic grades give excellent washout resistance for marine and humid duty.
- Shear stability — holds consistency under sustained high-shear loads.
- Wide compatibility — generally compatible with metals, many plastics and elastomers (useful for seals and O-rings).
The trade-off is that silica greases need careful formulation to control oil bleed and can be more expensive than a general lithium grease — so they are chosen for the demanding jobs, not as a universal grease.
Typical fumed silica grease properties
| Property | Typical value |
|---|---|
| Thickener | Fumed silica (SiO₂) |
| Base oil | Mineral or synthetic |
| NLGI grade | 1 to 3 |
| Worked penetration (60x) | 265–295 (typical NLGI 2) |
| Dropping point | None (does not melt) |
| Operating temperature | −40 to +250 °C |
| Water washout (ASTM D1264) | < 1% at 79 °C |
| Oxidation stability | High |
| Compatibility | Most elastomers & plastics |
Indicative values for a general-purpose NLGI 2 fumed silica grease — actual figures are tuned to the application (base-oil viscosity, colour, food-grade or not).
Applications
High-temperature bearings
Ovens, kilns, drying and furnace-area bearings where a soap grease would melt and run out.
Seals & O-rings
Its elastomer compatibility and inertness suit sealed joints, valves and O-rings, including in chemical service.
Chemical & process
Pumps and machinery exposed to acids, alkalis and solvents that would attack soap thickeners.
Marine & wet duty
Hydrophobic grades resist salt-water washout on deck gear and exposed fittings — see marine grease.
Custom fumed silica grease with Lubechem
We formulate fumed silica greases to your temperature, chemical and washout requirements — base-oil type and viscosity, silica loading for the target NLGI grade, oil-bleed control, colour and (if needed) food-grade compliance — then verify penetration, washout and oxidation in the lab. See the full grease formulation guide. The IP is yours.
Related guides
Fumed silica grease FAQ
What is fumed silica grease?
Fumed silica grease is a lubricating grease thickened with fumed silica — a very fine, high-surface-area form of silicon dioxide (SiO₂) — instead of a metal soap. The silica builds a network that holds the base oil without melting, giving a non-melting, water-resistant and chemically inert grease for demanding conditions.
Does fumed silica grease have a dropping point?
No. Because it is thickened by silica rather than a soap, fumed silica grease has no true dropping point and does not melt or drip at high temperature. Its useful upper limit is set by the base oil, not the thickener — typically around +250 °C.
What temperature can fumed silica grease handle?
A typical fumed silica grease operates from about −40 °C to +250 °C, and some formulations go higher. Because it does not melt, it holds consistency across that range far better than a soap grease of similar base-oil viscosity.
Where is fumed silica grease used?
It is used for high-temperature bearings, sealed joints and O-rings, chemically aggressive process equipment, and marine or wet applications — anywhere a conventional soap grease would melt, wash out or be chemically attacked. Food-grade variants exist for food and pharmaceutical machinery.
Is fumed silica grease compatible with rubber and plastics?
Generally yes — fumed silica grease is compatible with most elastomers and plastics, which is one reason it is favoured for seals and O-rings. As with any grease, the specific base oil should still be checked against sensitive elastomers before use.
Need a non-melting grease for extreme conditions?
From high-temperature bearings to chemical and marine duty, we formulate fumed silica greases to your exact requirement and prove them in the lab. The IP is yours.
Start a consultation →