3M Bondo Fiberglass Resin 28.7 fl oz with 0.37 fl oz Hardener — Waterproof, High‑Strength Repair Resin for Metal, Wood & Fiberglas

3M Bondo Fiberglass Resin is a high-strength polyester repair resin with included hardener, designed to rebuild, resurface, and seal metal, wood, fiberglass, and masonry.

Built for demanding repairs where strength and water resistance matter, this 28.7 US fl oz Bondo Fiberglass Resin (with 0.37 fl oz hardener) is formulated to work with fiberglass mat or cloth and as a stand-alone sealer. It integrates into the 3M Body Repair System at the Fill stage and accepts most paint systems, including gel coat and marine paints. Note: this product is intended for industrial/occupational use only and not for consumer sale or use.

How does this resin perform when rebuilding rusted metal or damaged fiberglass?

The polyester-based formula provides structural strength once cured, making it suitable to fill and reinforce rust-outs, holes, and delaminated areas when used with fiberglass reinforcement. It bonds well to prepared substrates and cures to a sandable, paintable surface.

• Use with fiberglass mat/cloth for strength and load-bearing repairs
• Cures to a sandable surface compatible with most paints
• Designed for stage 2 (Fill) in professional body repair workflows

Can I use this product outdoors and on marine projects?

Yes — the waterproof formula is formulated for exposure to moisture and is compatible with marine gel coats and marine paints when topcoated correctly. Proper substrate preparation and follow-up sealing or topcoat application are required to protect the repair in harsh environments.

• Water-resistant once fully cured for outdoor or boat use
• Accepts marine-grade paints and gel coat finishes
• Recommended use with appropriate primers and topcoats for long-term protection

What surfaces and preparation steps are needed for best results?

The resin works on fiberglass, wood, metal, and masonry. For optimal adhesion, remove loose material, clean contaminants, and roughen the surface so the resin can mechanically key into the substrate. Follow mixing ratios and apply within working time to avoid improper cure.

• Suitable for fiberglass, wood, metal, and masonry repairs
• Clean, degrease, and abrade surfaces before applying
• Mix the supplied 0.37 fl oz hardener accurately for reliable cure times

How does the included hardener affect mixing and cure control?

The small-dose hardener is supplied for convenient, accurate mixing with the resin. Proper measurement ensures predictable pot life and cure speed; altering hardener amount can change work time and final properties. Always follow safety and mixing instructions for consistent results.

• Comes with a matched hardener for correct mixing proportions
• Accurate hardener dosing yields reliable work time and strength
• Follow manufacturer guidelines to avoid incomplete cure or brittleness

Who is this for? This Bondo Fiberglass Resin kit is aimed at professional body shops, marine repair technicians, boatbuilders, and industrial maintenance teams who need a durable, waterproof polyester resin for structural repairs and resurfacing. It suits users who follow occupational safety and product handling protocols and who will finish repairs with appropriate primers and topcoats. Remember: this product is intended for industrial/occupational use only, not for consumer sale or household use.