FILCO® 303I is an epoxy resin formulated into a non-ionic water emulsion, specifically intended as a film former within glass fiber sizings. Presenting as a milky liquid, its defining traits encompass its purity as a pure epoxy resin, an epoxy equivalent weight of 200g, a narrow particle size distribution, and exceptional mechanical shear stability even when the emulsion is diluted.

Functions: Film Former

Chemical Family: Epoxy & Epoxy Derivatives

Compatible Polymers & Resins: Unsaturated Polyester (UPE)

Processing Methods: Filament Winding

Technical Data Sheet

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Identification & Functionality

Composite Materials Functions

Features & Benefits

Characteristics of Film

Characteristics of the film:

  • Clear
  • Tacky film
  • Glass transition temperature Tg=-20°C
  • Compatible with unsaturated polyesters and other thermosets
  • Very quickly soluble in styrene

Main product characteristics: 

  • Pure epoxy resin
  • Epoxy Eq. Wt. = 200 g
  • Narrow particle size distribution
  • High mechanical shear stability of diluted emulsion

Applications & Uses

Compatible Polymers & Resins
Compatible Reinforcements
Composites Processing Methods
Processing Information

FILCO® 303I is suggested as film former for glass fiber sizes for

  • Roving for filament winding
  • Panel roving
  • Woven roving


Physical Form
Milky liquid
Typical Properties
ValueUnitsTest Method / Conditions
Viscosity (at 25°C, #3, 20rpm)max. 1000mPa.sMA143LFE
Solid Content50 - 52%MA145LFE
pH (at 20°C)6 - 8.5-MA148LFE
Epoxy Equivalent Weight (on dry resin)180 - 215gMA149LFE
Particle Size Distribution
ValueUnitsTest Method / Conditions
Average Particle Size200 - 800nmMA147LFE

Packaging & Availability

Regional Availability
  • Canada
  • Mexico
  • USA

Storage & Handling

Shelf Life
8 months
Storage and Shelf Life Conditions

FILCO® 303I should be stored in closed containers away from direct sun rays, at temperature between +5 and +30°C. In these conditions maximum suggested storage time is 8 months from production, in the original package. After that date product must be rechecked. During storage a slight settlement can take place, which can easily be eliminated by careful stirring. Prevent from freezing.