Premium Chemically Inert Silicone Oil for Professional Molding and Lubrication Applications
Silicone Oil 350 cSt is a moderately fluid, colorless, and chemically inert polydimethylsiloxane (PDMS) fluid with a viscosity of 350 cSt and a density of 0.970 g/cm³ at 25°C. With a flash point of over 300°C, a pour point of -50°C, and a surface tension of 21.1 mN/m, Silicone Oil 350 cSt offers an excellent balance between fluidity, film retention, and thermal stability. The 350 cSt grade is considered by professionals to be the most commonly used grade for softening silicones: fluid enough for even mixing, viscous enough for a durable film. Food grade version (PC grade) available in accordance with EC 1935/2004 and FDA 21 CFR 173.340.
Key Benefits
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Flash point >300°C: High thermal stability – safe to use at elevated temperatures in industrial processing and lubrication applications.
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Viscosity 350 cSt at 25°C: Most commonly used grade for silicone additive – optimal balance between mixability and durable film retention on molds and surfaces.
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Pour point -50°C: Retains its fluid properties at low temperatures – suitable for applications in cold environments.
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Surface tension 21.1 mN/m: Excellent wetting of surfaces – uniform spread as a release coating on molds and dies.
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Food grade compliant with EC 1935/2004 and FDA 21 CFR 173.340: Certified for applications requiring indirect food contact – usable as an antifoaming agent or lubricant in the food industry.
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Chemically non-reactive: Does not react with addition or condensation silicones, most plastics and elastomers – safe as an additive without unwanted side reactions.
Typical Applications
- Release agent for rubber, polyurethane, epoxy and metal injection molding – durable release film on complex mold surfaces
- Additive in addition and condensation silicones (1–10%) to reduce hardness and increase fluidity – the most commonly applied grade for this use
- Antifoaming agent in non-aqueous systems – effective in small quantities
- Lubricant for plastic and elastomer surfaces – excellent lubricating properties without material degradation
- Electrical insulation and damping fluid in electrical and electronic equipment
- Manual smoothing of spatulated silicone molds – the 350 cSt viscosity is ideal for smooth spreading by hand or brush
Processing instructions (as an additive in silicones):
- Weigh the desired amount of component A of your silicone and add component B according to the mixing ratio information sheet.
- Stir the mixture thoroughly.
- Add the silicone oil to the silicone mixture and stir again. Vary between 1 and 10% oil based on the total weight. An addition of approximately 8% reduces the Shore A hardness by about 3 to 5 points.
- Keep the percentage below 10%: more than 10% oil can unacceptably reduce the final strength of the cured silicone.
- Process the mixture within the pot life of your silicone.
⚠️ Note: Silicone oils do not cross-link in silicone and will slowly exude under sustained stress or over time, leaving a greasy layer on the mold. Take this into account for long-term mold applications.
⚠️ Thermal stability: Polydimethylsiloxane slowly begins to thermally degrade above approximately 150°C, releasing formaldehyde gas, among other things. For applications at temperatures above 150°C, it is recommended to ensure good extraction or ventilation.
Compliance & Certification
Silicone Oil 350 cSt in the PC grade (food-safe version) complies with EC 1935/2004 and EC 10/2011 for materials in contact with foodstuffs, with FDA 21 CFR 173.340 (antifoaming agent as a secondary direct food additive), and with the BfR recommendation "XV Silicones". The 350 cSt variant is also included in EU Directive 95/2/EC under E 900 polydimethylsiloxane. For standard industrial applications, the standard technical datasheet values apply.
Produced by AToro B.V., specialist in high-quality silicones and silanes for industrial and technical applications, based in the Netherlands.
Professional Support
Are you unsure about the correct viscosity for your application, or do you have questions about the usability of silicone oil in a certified food-grade environment? Contact us for technical datasheets, processing manuals, or product advice.
