Woven Glass Fabric vs Woven Roving: Reinforcement Selection for Resin Infusion

Both materials are woven from high-strength electrical-grade (E-Glass) filaments, but they differ drastically in filament grouping and aerial weight:

• Fine Woven Glass Fabric: Produced using lightly twisted fine yarns. Standard weights range from 45 g/m² to 200 g/m². The resulting fabric is smooth, tight, and thin (0.05 to 0.20 mm per cured ply).
• Woven Roving (WR): Manufactured from heavy, untwisted continuous filament rovings woven into a coarse grid. Standard weights range from 400 g/m² to 800 g/m². Woven roving is thick, heavy, and engineered for rapid laminate thickness accumulation.

In vacuum resin infusion (VIP) and high-quality mold construction, laminating engineers follow a proven layering strategy:

• The Print-Through Problem: Because woven roving has thick, coarse tows, placing woven roving directly against the gelcoat or mold face causes resin shrinkage marks ("print-through"), creating an uneven, corrugated exterior finish.
• The Skin Ply Solution: Best practice is to apply 1 to 2 plies of fine woven glass fabric (or surface veil) against the gelcoat. This creates a dense, resin-rich barrier layer that completely prevents the coarse roving pattern from telegraphing to the finished surface.
• Infusion Permeability: Coarse woven roving features open inter-tow channels that act as natural resin distribution pathways under vacuum, significantly reducing infusion fill times in large hulls, wind turbine roots, and storage tanks.

An essential engineering application of fine glass fabric is galvanic corrosion isolation in carbon fiber assemblies. Carbon fiber is electrically conductive and has a high galvanic potential. When in direct contact with aluminum or steel fasteners, it accelerates metal corrosion.

By placing a single insulating ply of fine woven glass fabric between the carbon laminate and metal mounting hardware, engineers create an electrically non-conductive barrier, eliminating galvanic corrosion entirely.