521 Marine Grade Epoxy Resin

Bonds with Fiberglass, Metals, Wood, and Composite Fabrics


521 Marine Epoxy Resin bonds with fiberglass, metals, wood, and composite fabrics and features superb strength, durability, and moisture resistance. The 521 Epoxy cures to a high-strength solid, suitable for laminating, bonding, fairing, coating, and reinforcing. Self-leveling properties are ideal for coating and laminating. Viscosity is favored for wetting out fiberglass cloth and other reinforcement fabrics easily. Use this versatile epoxy resin with 521 fast or slow hardener to complete a number of boat building, repair, and restoration projects.

  • Bonds with fiberglass, reinforcement fabrics, wood, etched aluminum, and bare steel and lead
  • Makes a strong filleting or fairing compound or adhesive 
  • Excellent thin-film characteristics provide smooth flow-out and self-leveling ideal for coating and laminating
  • Easy to measure and mix using pre-calibrated 5:1 Epoxy Pumps (included), or by volume
  • Easy to apply by brush, roller, syringe, spreader, or by pouring onto wood, fiberglass, reinforcement fabrics, etched aluminum, bare steel, and lead.
  • Kit comes with resin, hardener, pumps, and pump calibration instructions.
  • 521 Marine Epoxy Resin can be used with our 521 Fast or Slow Hardener, depending upon your application.

Bonds To

  • Fiberglass
  • Reinforcement Fabrics
  • Wood
  • Etched Aluminum
  • Bare Steel
  • Lead
  • Granite
  • Tile


  • High-Strength Solid
  • Moisture-Resistant
  • Simple Measure & Mix
  • Self Leveling
  • Cures Amber
  • Easily Sand and Shape

Marine Grade Epoxy Versions

521 Fast Hardener

Fast Hardener is a perfect selection for applications requiring quick working time and for use in cooler climates (recommended use 60-70°F)
  • Minimum recommended temperature (Fast Hardener): 60°F - In cooler temperatures, the 521 Epoxy Resin/Fast Hardener mixture remains workable to give you adequate time for application, and it speeds up cure time.
  • The recommended temperature for use and dispensing via pump: 60-70°F
  • Pot life @ 70°F: 12 minutes (Fast Hardener)
  • Set time @ 70°F (thin film): 6 hours
  • Cure time @ 70°F (thin film): 1 to 4 days
  • Hardener Color: 521 Fast (Dark Amber)

521 Slow Hardener

Slow Hardener is a perfect selection for applications requiring more working time and for use in warmer climates (recommended use above 80F)
  • Minimum recommended temperature (Slow Hardener): 80°F - Slow Hardener buys you a little more working time in warmer temperatures that tend to reduce working time and cure time of epoxy resins.
  • The recommended temperature for use and dispensing via pump: above 80°F
  • Pot life @ 80°F: 30 minutes (Slow Hardener)
  • Set time @ 80°F (thin film): 10 hours
  • Cure time @ 80°F (thin film): 1 to 4 days
  • Hardener Color: 521 Slow (Clear-Light Amber)

Compatibility: Pro Marine Supplies 521 Epoxy Resin can be used interchangeably with 521 Fast or Slow Hardeners.

Safety Information

Always wear protective clothing and equipment to protect your eyes, skin, and lungs when working with 521 Marine Grade Epoxy Resin and Hardeners. Personal protective clothing should include appropriate gloves, safety glasses or goggles, a respirator, and protective clothing.

*Please note: The 521 Marine Epoxy is not meant for clear coating, Table Top, Counter, or Art Applications. Please see our Table Top Epoxy for those types of applications.