Regular price
$16.49
Sale price$21.99you save $5.50
Use 520 Slow Hardener when you are working on a large lamination project. The slow gel time and cost effective pricing will make you a happy boat builder. Only use this product at a 5:1 by volume mix ratio with the Marine Epoxy Traditional Resin.
5 to 1 mix ratio by volume with Traditional Marine Resin
20 min pot life
1.5 hr work time at 70F degrees
Ideal for sealing wood surfaces, bonding applications, marine construction, marine repair, cold molding process for fabricating wood and fiberglass structures
Great for laminating wooden FRP construction boat hulls or other projects
Can be used with our fillers and for gluing, bonding and filleting
Cost effective laminating hardener
Purchase with Traditional Marine Resin for a complete system:
Marine Hardener 320 Clear Finishing Topcoat - 30 min pot life / 4 hr work time at 70F degrees / 3:1 mix ratio with Traditional Marine Resin / Non-blushing ultra crystal clear finishing topcoat
Marine Hardener 520 Slow - 20 min pot life / 1.5 hr work time at 70F degrees / 5:1 mix ratio with Traditional Marine Resin / Use for structural lamination and strength
Marine Hardener 510 Fast - 12 min pot life / 1 hr work time at 70F degrees / 5:1 mix ratio with Traditional Marine Resin / Use on small to medium sized structural lamination projects and fillet or to repair and fill holes.
From wooden boats to fiberglass hulls and etched aluminum surfaces, our 5:1 epoxy resin system excels across a wide range of materials. Use it with fiberglass cloth, carbon fiber, and other reinforcement fabrics, or apply it directly to wood, bare steel, or lead. It’s also ideal for small-scale metal and plastic repairs—just like JB Weld, but marine-ready.
Moisture-Resistant Cure
This system cures with excellent moisture resistance, making it a favorite for boatbuilding, hull repairs, and even wet environments. Use it for laminating, vacuum bagging, or as a clear, protective sealer on table tops and countertops. When used without cloth, it forms a durable barrier against the elements.
Smooth, Self-Leveling Application
Low viscosity and optimized wet-out mean this epoxy flows smoothly across cloth, wood grain, or composite surfaces. It’s great for filling, fairing, and forming strong adhesive bonds. Add fillers to create high-strength filleting compounds, or use it straight for a clean, uniform coat.
Control Your Cure Time
Choose between Fast (510 Hardener) and Slow (520 Hardener) speeds depending on your timeline and ambient temperature. Fast hardener is great for quick turnarounds or cooler temps, while Slow hardener offers extended working time and higher heat resistance for large layups or warm environments.
Easy, Accurate Mixing
Available in Quart and Gallon kits, each set includes calibrated metering pumps for foolproof 5:1 mixing – one full pump of resin, one full pump of hardener. No guesswork, no wasted material. Whether you’re sealing a hull or tackling a small fix, you’ll get a consistent, dependable mix every time.
