Silicone paste and silicone grease: applications, compatibility, and selection
Silicone paste and silicone grease lubricate, seal, and protect where conventional mineral oil greases would come into contact with plastics and elastomers. This guide explains the differences, material compatibility, and typical applications.
At a glance: Silicone paste or silicone grease?
Silicone grease is a soft, long-term stable lubricating grease based on silicone oil with a thickener, ideal for O-rings, seals, and fittings, especially in contact with plastics and elastomers. Silicone paste is usually more highly filled and more viscous, suitable for sealing, separating, and as an assembly aid. Both are electrically insulating, temperature-stable, and aging-resistant, and compatible with many materials. The respective technical data sheet is binding for compatibility and temperature range.
What distinguishes silicone lubricants
Silicone-based pastes and greases use silicone oil (polydimethylsiloxane) as the base oil. This results in properties that mineral oil-based products do not offer: a wide temperature range, low temperature dependence of viscosity, good aging and oxidation stability, electrical insulating effect, and very good compatibility with many plastics and elastomers.
Silicone grease vs. silicone paste
| Feature | Silicone grease | Silicone paste |
|---|---|---|
| Consistency | soft, lubricating | viscous, more highly filled |
| Main purpose | Lubricating, O-ring care | Sealing, separating, assembly |
| Typical applications | Fittings, valves, seals | Threads, flanges, connectors |
| Common | electrically insulating, temperature-stable, material-friendly | such as grease |
Reference values; the specific suitability depends on the product and application and must be checked in the respective technical data sheet.
Typical Applications
- O-rings and seals: reduces friction during assembly and operation, protects elastomers from drying out.
- Valves and fittings: smooth operation, also in sanitary and drinking water applications (check for approvals).
- Connectors and contacts: Protection against moisture; electrically insulating.
- Plastic-plastic and plastic-metal pairings: where mineral oils could attack or embrittle the plastic.
Compatibility: the most important selection criterion
Silicone lubricants are compatible with many, but not all, materials. For silicone elastomers (swelling) and certain plastics, a compatibility test is advisable. For applications with approval requirements, such as drinking water or areas with possible, technically unavoidable food contact (NSF-H1 registration), only a product registered for that purpose may be used.
What to consider when selecting
- Temperature range of the application,
- Materials to be lubricated or sealed (compatibility),
- Load and desired consistency (grease vs. paste),
- any approvals (drinking water, NSF H1),
- electrical requirements (insulation).
Silicone oil, grease, or paste: where is the difference?
All three are based on silicone oil (polydimethylsiloxane). Silicone oil is the liquid base product and is used for lubricating, releasing, and insulating. Silicone grease is produced by adding a thickener and remains stable at the lubrication point. Silicone paste is more highly filled, more viscous, and thus ideal as a sealing and assembly aid. The choice depends on whether the product should flow, adhere, or seal.
Practical tips for application
- Apply thinly and precisely; excess attracts dust.
- Clean the seal and groove before application.
- For O-rings, wet the entire circumference, not just spot areas.
- For electrical contacts, pay attention to the insulating effect; only apply to non-current-carrying sealing surfaces.
Frequently asked questions
Is silicone grease suitable for drinking water?
Only products with the appropriate approval (e.g., according to the relevant drinking water regulations). Suitability is stated in the technical data sheet and in the respective certification.
Does silicone grease attack rubber?
As a rule, silicone is very gentle on elastomers. With silicone elastomers, swelling may occur; in case of doubt, check compatibility.
Does silicone paste conduct heat?
Standard silicone paste is insulating. For heat dissipation, there are filled thermal pastes, which are a different product with a high filler content.
Sources and technical basis
The information is based on manufacturer data sheets and generally recognized tribological principles. Compatibility, temperature range, and any approvals are product-dependent and must be taken from the respective technical data sheet.
How SILITECH supports
Provide us with the component, material pairing, and temperature range, and we will recommend suitable silicone pastes or greases and supply the corresponding technical data sheets.
