DOWSIL OS-20
Harmonization Code : 3208.20.90 | Paints and varnishes that are dispersed or dissolved in a non aqueous medium

Main features
- Immersion, Spray, or Wipe Cleaning
- Very-Low-Residue Complete Evaporation
- 0 g/L US VOC-Exempt Solvent
Product Description
DOWSIL™ OS-20 Fluid is a one-part, clear, colorless volatile methylsiloxane fluid used as a precision cleaning agent, surface-preparation solvent and process carrier. It is compatible with most plastics and surface coatings and can be applied by immersion, spray or impregnated wipes. The fluid has a typical dynamic viscosity of 0.8 cP and surface tension of 16.5 dynes/cm at 25°C, supporting easy spreading across complex or multi-material parts. It is an effective solvent for nonvolatile silicone materials and evaporates completely at room temperature with very low residual nonvolatile content, allowing cleaned surfaces to proceed to painting, bonding or sealing after compatibility verification. In the United States, DOWSIL™ OS-20 Fluid is VOC exempt (VOC = 0 g/L) and is certified as a Clean Air Solvent by the California South Coast Air Quality Management District. The product is classified as a flammable liquid.
Key features
- Multi-material cleaning: Compatible with most plastics and surface coatings and documented for cleaning plastics, metals and other surfaces; verify compatibility on the actual materials.
- Multiple application methods: Suitable for immersion, spray and impregnated-wipe cleaning according to the part geometry and contamination level.
- Low-viscosity spreading: Typical dynamic viscosity is 0.8 cP and surface tension is 16.5 dynes/cm at 25°C.
- Low-residue evaporation: Evaporates completely at room temperature with very low residual nonvolatile content.
- Silicone solvency and carrier use: Removes nonvolatile silicone materials and can serve as a solvent or carrier for silicone oils and greases.
- US VOC status: VOC exempt in the United States at 0 g/L and certified as a Clean Air Solvent by the California South Coast Air Quality Management District.
Applications / Suitable for
- Cleaning plastics, metals, boards and assemblies, components and housings
- Rinsing parts after cleaning with stronger cleaning agents
- Aerosol cleaning of industrial optics and spectacle lenses
- Impregnated wipes for lightly contaminated components
- Surface preparation before painting, bonding or sealing
- Solvent or carrier for silicone oils, greases and selected industrial formulations
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Thermal Properties
Physical Properties
Additional Information
DOWSIL™ OS-20 Fluid
DOWSIL™ OS-20 Fluid is a one-part volatile methylsiloxane fluid for precision cleaning, surface preparation and carrier use. Its low surface tension and 0.8 cP viscosity support spreading across complex parts, while compatibility with most plastics and surface coatings suits multi-material assemblies. The fluid evaporates completely and can remove nonvolatile silicone contamination before painting, bonding or sealing.
Supplier product-page image for DOWSIL™ OS-20 Fluid.
Typical properties
Values below are typical and are not intended for use in preparing specifications. Conditions and methods are shown where available.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Appearance | Clear, colorless liquid | — | As supplied |
| Flash point, closed cup | 34 | °C (94 °F) | Closed cup |
| Boiling point | 152 | °C (306 °F) | At 760 mm Hg |
| Vapor pressure | 3.9 | mm Hg | At 25°C (77°F) |
| Dynamic viscosity | 0.8 | cP | At 25°C (77°F) |
| Specific gravity | 0.82 | — | At 25°C (77°F) |
| Surface tension | 16.5 | dynes/cm | At 25°C (77°F) |
| Freezing point | -82 | °C (-115 °F) | Typical value |
| Drying rate | 0.7 | relative | Butyl acetate = 1; ASTM D-1901 |
| Kauri-butanol value | 15 | — | Typical value |
| Lower explosive limit | 0.9 | vol % | Flammability property |
| Upper explosive limit | 13.8 | vol % | Flammability property |
| Autoignition temperature | 350 | °C (662 °F) | Typical flammability property |
| Documented packaging | 25 L pails; approx. 200 L drums | — | Availability may vary by region |
Cleaning and application
Select equipment and procedures designed for flammable liquids. Verify compatibility on the actual substrate before use, particularly for sensitive coatings or multi-material parts.
Supported cleaning methods include immersion, spray and impregnated wipes.
Store in the original, unopened container at or below 54°C; the documented shelf life is four years from the date of manufacture. Keep containers tightly closed in a cool, well-ventilated area away from heat, sparks, open flames and strong oxidizing agents. DOWSIL™ OS-20 Fluid is a Category 3 flammable liquid and can accumulate static charge. Ground and bond containers and transfer equipment, use non-sparking tools and explosion-proof ventilation, and review the current Safety Data Sheet and container label before handling.
Cleaning, surface preparation and carrier applications
DOWSIL™ OS-20 Fluid is documented for precision cleaning and carrier uses across parts, assemblies and formulations. Confirm material compatibility and fire-safety controls for the actual process.
Evaluate DOWSIL™ OS-20 Fluid for your cleaning process
Krayden can help review substrate compatibility, cleaning method, evaporation requirements, flammability controls and whether DOWSIL™ OS-20 Fluid or another volatility grade fits your process. Contact us to discuss part materials, contamination type, equipment, downstream painting or bonding, and sample or supply requirements.





















