West System C105B Epoxy Resin – 3.74 L (.98 Gal)

West System C105B Epoxy Resin – 3.74 L (.98 Gal)

The same clear, light amber, low-viscosity epoxy resin as the C105A — in a larger near-gallon format suited for extended projects, production builds, and multi-stage repairs. C105B delivers deep penetration into wood fiber and fiberglass laminates, self-levels under roller application, and cures across a wide temperature range to a hard, sandable finish.

Must be paired with a compatible West System hardener. Ratio and working time are determined by hardener selection.

Key Features

• Low viscosity (~1000 cP at 70°F / 21°C) for thorough penetration into wood and fiberglass substrates
• Self-leveling — ideal for roller application on horizontal surfaces and large flat panels
• Cures across a wide temperature range for flexible use in varying conditions
• Sands, shapes, and paints cleanly after full cure
• Excellent adhesive base when combined with thickening fillers to control sag on vertical surfaces
• Relatively high flash point for safer handling in enclosed spaces
• 3.74 L size reduces per-unit cost for larger jobs

Compatible Hardeners

Select a hardener based on your working time requirements and ambient temperature:

• West System C205 Hardener – 814 ml — Standard cure, all-season versatility
• West System C205 Hardener – 208 ml — Compact size for smaller mixed batches
• West System C209SB Extra Slow Hardener – 1.24 L — Extended pot life for large pours or warm-weather work
• West System C207SA Special Clear Hardener – 315 ml — For clear-coat and bright-finish applications

Related Products

• West System C105A Epoxy Resin – 946 ml — Smaller format for targeted repairs and smaller jobs
• West System 733W Fiberglass Reinforcing Tape – 6" x 10' (2-Pack) — Structural tape for seams and corners
• West System Biaxial E-Glass Fabric – 17 oz., 50" x 20 yd. — High-performance laminating fabric for structural builds

Parts Desk Insights

Best Use Cases: The C105B is the practical choice when a job requires more resin than a single 946 ml unit can provide — hull encapsulation, multi-layer lamination schedules, large fairing jobs, or any project where mixing multiple small units would create ratio inconsistency risk. It’s well-suited for boatyard professionals and serious DIY builders working on full hull repairs, deck replacements, or new plywood/strip-planked builds where consistent resin supply across sessions matters.

Tip: Store partially used containers with the lid sealed tightly and use a pump dispenser for accurate metering. Incorrect mix ratios are the leading cause of soft or tacky cures — always measure by volume or weight. For high-volume production work, consider the West System C105C Resin – 16.46 L for even greater economy per litre.