U.S. Chemical & Plastics Duraglas Fiberglass Filled Body Filler 1 Gallon — reinforced, for rust-outs and large hole repairs

Duraglas Fiberglass Filled Filler is a one-gallon, fiberglass-reinforced body filler designed to restore rusted panels, holes and cracks on metal and fiberglass surfaces with high structural strength.

Duraglas from U.S. Chemical & Plastics is the original short-strand fiberglass body filler engineered for demanding automotive and marine repair work. Formulated with chopped fiberglass fibers and a supplied cream hardener, it offers a tougher, more durable repair than conventional polyester putties. Supplied as a blue-green paste, this product bonds to metal, aluminum, fiberglass, wood, masonry and concrete for patching, filling and rebuilding damaged areas before finishing.

How does Duraglas handle rust-outs and large holes?

Duraglas contains short-strand fiberglass that adds tensile strength across damaged zones, making it suitable for filling rust-throughs and larger voids that would defeat standard body fillers. For extensive damage it integrates with fiberglass cloth to create a composite repair that resists collapse and flexing.

• Use with fiberglass cloth for structural bridging of large openings
• Reinforced paste prevents sinking in deep fills
• Works over weld areas and bond seams to rebuild metal contours
• Waterproof and rustproof properties improve longevity

What surfaces can I apply Duraglas to and how do I prepare them?

Duraglas adheres to a wide range of substrates including steel, aluminum, fiberglass, wood, masonry and concrete when surfaces are properly cleaned and abraded. Remove loose rust, old paint and contaminants, then sand to a clean, roughened profile for best mechanical adhesion.

• Clean oil, grease and dirt before application
• Sand or grind to bare metal or roughen gelcoat on fiberglass
• Prime bare ferrous metal or aluminum if recommended for top coat compatibility
• Apply at recommended 2% hardener mix by weight (approx. 50:1 ratio)

How do I mix, apply and finish Duraglas for a lasting repair?

Measure the supplied cream hardener at about 2% by weight (roughly a 50:1 ratio) and thoroughly blend into the filler until uniform. Shape the filler while it’s still workable, allow it to cure, then sand to shape; finish with All-Metal or a compatible finishing putty before final priming and paint.

• Mix at 2% hardener by weight; small test batches recommended
• Pack into cavities or spread over cloth for reinforced patches
• Cure fully before sanding and profiling
• Top coat with All-Metal or finishing putty for a waterproof finish

Will Duraglas withstand marine or exterior exposure?

Duraglas is formulated to be waterproof and rustproof once cured, making it appropriate for exterior and marine applications when properly sealed and top-coated. Use in conjunction with recommended top coats and surface preparation to maintain durability in wet or corrosive environments.

• Fiberglass reinforcement improves resistance to moisture and flex
• Recommended top coat seals the repair for marine use
• Suitable for hull repairs, transom repairs and exterior panels
• Not a substitute for structural laminates — use cloth and proper layup when needed

Who is this product for? Duraglas is aimed at automotive restorers, collision repair technicians, boat owners and DIYers who need a heavy-duty filler that rebuilds and reinforces damaged panels. If you require a stronger, fiberglass-filled alternative to standard polyester putties for rust repair, weld areas, holes or fiberglass seam work, Duraglas provides a reliable, long-lasting solution that integrates with fiberglass cloth and accepts finishing putties and top coats.