Silicone-Free Defoamer for UPR / Gelcoat Systems
Key Features
- Zero silicone — eliminates fisheye, cratering, and paint adhesion failure risk
- Mandatory for gelcoat and IMC systems requiring direct topcoat paint compatibility
- Effective foam control in UPR, VER, and methacrylate-based surface coat resins
- No migration to cured surface — paintable substrates without solvent wash
- Available in fluorocarbon or organic ester active ingredient variants
Silicone-Free Defoamer for UPR/Gelcoat Systems is an organic air-release and defoaming additive formulated without polydimethylsiloxane (PDMS), making it suitable for use in gelcoat formulations, in-mold coating systems, and composite resin applications where silicone contamination of the cured surface must be avoided. Conventional silicone defoamers can migrate to the surface of cured composites and gelcoats, creating silicone-rich domains that cause fisheye, cratering, and poor adhesion of secondary paint or gel coatings. Silicone-free grades eliminate this contamination risk while still providing effective foam control.
Silicone-free defoamers for composites typically employ one or more of the following active ingredients: fluorocarbon-modified surface-active agents (ultra-low surface tension, no silicone), mineral oil and ester blends with wax components, or specially modified fatty acid polyalkylene glycol esters. These materials break foam through surface spreading and Gibbs-Marangoni effect disruption at the air-bubble interface, providing defoaming efficacy comparable to silicone at optimized dosage.
In gelcoat formulations (pigmented UPR surface coats), silicone-free defoamers are mandatory when the cured gelcoat surface must accept automotive or marine topcoat paints without solvent wash or mechanical abrasion preparation steps. They are also required in in-mold coating (IMC) systems applied under pressure in closed molds, where silicone contamination would prevent subsequent paint adhesion to the extracted part. Available in both concentrate and pre-diluted forms for convenient addition to gelcoat paste formulations.
Specifications
| Parameter | Value |
|---|---|
| Appearance | Clear to yellowish liquid |
| Flash point | >61°C |
| Typical dosage | 0.05–0.3% by weight in resin |
| Density (20°C) | 0.850–0.980 g/cm³ |
| Silicone content | None detectable |
| Active ingredient | Fluorocarbon or organic ester-based defoamer (silicone-free) |
| Viscosity (25°C) | 50–500 mPa·s |
Applications
FAQ
Silicone defoamer (PDMS-based) is generally more efficient per unit dosage than silicone-free alternatives — it typically works at 0.01–0.05% while silicone-free defoamers may require 0.05–0.3% for equivalent defoaming. However, in gelcoat and surface coat applications, the surface quality benefit of silicone-free far outweighs the higher dosage cost. In backing laminate applications where surface contamination is not a concern, silicone defoamer is preferred for its higher efficiency. The choice should be driven by whether the cured surface will be painted or coated.
Direct Contact
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