10 Best Epoxy Slow Hardener of 2025

Tested and Reviewed: Top 10 Epoxy Slow Hardener deals with expert ratings from 8.1 to a perfect 10

March 2026 Edition

Editor's Choice

9.7

West System

West System 206-A Slow Hardener

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Editor's bottom line:

“This epoxy slow hardener is the best one we tested. In terms of quality, brand and price, we couldn't ask for more.”

Main Highlights

206 SLOW HARDENER is a low-viscosity epoxy curing agent. It is useful in a majority of bonding situations, and when extended working time and cure time are needed.
MIX WITH WEST SYSTEM 105 Resin in a five-part resin to one-part hardener ratio. The resulting cured epoxy is a rigid, high-strength, moisture-resistant solid. The combination of 105 Resin/206 Slow Hardener has excellent bonding, coating and barrier coating properties.
CURES AT TEMPERATURES as low as 60°F (16°C). Will cure faster at warmer temperatures. Pot life at 72°F is 20 to 25 Minutes. Cures to a solid state in 10 to 15 hours. Cures to maximum strength in 1 to 4 days. Minimum recommended working temperature is 60°F (16°C).
PAIR WITH WEST SYSTEM 105-A Epoxy Resin. Blend with with WEST SYSTEM 105 Epoxy Resin at a 5-parts resin to 1-part hardener ratio.
EASILY MODIFIED with WEST SYSTEM Fillers, Additives, and Pigments to suit the job at hand, whether coating, applying fiberglass, structural bonding, or fairing. Not intended for clear coating.

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9.5

West System

West System 206-B Slow Hardener

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Main Highlights

Slow-curing epoxy hardener for extended working time WEST SYSTEM 206 slow hardener is a Made in the USA low-viscosity epoxy curing agent designed for bonding applications at room temp (60 degrees) or higher.
Develops high-strength, moisture-resistant bonds When cured, 206 produces a rigid, high-strength solid that is functionally waterproof and highly resistant to moisture vapor in structural and protective applications.
Designed to mix with WEST SYSTEM 105 resin Used with WEST SYSTEM 105 epoxy resin at a 5-parts resin to 1-part hardener ratio, this combination provides excellent bonding and barrier coating performance.
Predictable cure profile across temperatures At 72°F (22°C), pot life is 20 to 25 minutes, cures to a solid state in 10 to 15 hours, and reaches maximum strength in 1 to 4 days. Minimum recommended working temperature is 60°F (16°C).
Adaptable with fillers and fiberglass applications The 105 resin and 206 hardener system can be modified with WEST SYSTEM fillers, additives, and pigments for coating, fiberglass work, structural bonding, or fairing. Not intended for clear coating.

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9.5

TotalBoat

TotalBoat 5:1 Epoxy Slow Hardener 6 Ounces (for Quart of Resin),Clear Amber

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Main Highlights

Low viscosity epoxy curing agent for use with TotalBoat 5:1 epoxy resin in warmer working environments
Compatible with all traditional 5 part resin to 1 part hardener marine epoxies
Combine with resin to create a rigid, high strength solid with excellent bonding and coating properties
Dispense with TotalBoat 5:1 pumps to ensure correct ratio
Available in three sizes for quart, gallon, and 5 gallon resin

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9.2

TotalBoat

TotalBoat 5:1 Epoxy Slow Hardener - 25 Ounces to Mix with Gallon of Resin

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Main Highlights

Low viscosity epoxy curing agent for use with TotalBoat 5:1 epoxy resin in warmer working environments
Compatible with all traditional 5 part resin to 1 part hardener marine epoxies
Combine with resin to create a rigid, high strength solid with excellent bonding and coating properties
Dispense with TotalBoat 5:1 pumps to ensure correct ratio
Available in three sizes for quart, gallon, and 5 gallon resin

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9.0

TotalBoat

TotalBoat High Performance Slow Hardener (Pint),Clear

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Main Highlights

Part 2 of a two-part, low-viscosity epoxy resin system thats easy to use for clear coating, laminating, layups, and vacuum bagging. Low odor and low VOCs make it great for shop or indoor use. Blush-free formula does not require time-consuming washdowns between coats.
Provides the longest pot life and cure time at room temperature.
For use with TotalBoat 2:1 High Performance 2:1 Epoxy Resin. Simple 2 parts resin to 1 part hardener mix ratio makes it easy to get a strong, ultra-clear cure every time, especially using TotalBoat 2:1 Pumps (sold separately).
Blend mixed epoxy resin with fillers to create a strong adhesive, fairing compound, or filleting compound.
Available in Pint, Half Gallon, and Gallon sizes

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8.8

West System

West System 105A Epoxy Resin (32 fl oz) Bundle with 206A Slow Epoxy Hardener (7 fl oz). Also Includes one Resin and one Hardener Pump.

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Main Highlights

CONVENIENT EPOXY BUNDLE contains one can of WEST SYSTEM 105-A Resin (32 fl oz), WEST SYSTEM 206-A Slow Hardener (7 fl oz), and one set of calibrated 300 Mini Pumps. 206 Slow Hardener is a low-viscosity epoxy curing agent for use when extended working time or a longer cure time is needed. It also provides adequate working time at higher shop temperatures.
v105 EPOXY RESIN is a clear, pale yellow, low-viscosity liquid epoxy resin. Blended with 206 Slow Hardener at a 5:1 ratio, it cures to a hard, solid plastic with superior physical properties. It will wet out and bond with wood fiber, fiberglass, reinforcing fabrics and a variety of metals. (206 Slow Hardener is not intended for clear coating.)
POT LIFE AT 72°F (22°C) is 20 to 25 minutes. Cures to a solid state in 10 to 15 hours. Cures to maximum strength in 1 to 4 days. Minimum recommended working temperature is 60°F (16°C). Does not contain VOCs and has relatively high flash point and no solvent odor, making it much friendlier to use than styrenated resins.
EXCELLENT FOR COATNG OR BONDING, this epoxy is easily modified with WEST SYSTEM fillers, pigments, and additives to suit an enormous variety of construction and repair projects, including fiberglass boat repair, strip kayak and canoe construction. Resin viscosity is approximately 1000 centipoise at 72°F (22°C)
INCLUDES CALIBRATED PUMPS that dispense 105 Resin & 206 Slow Hardener at the correct 5-part resin to 1-part hardener mix ratio. One pump stroke of resin for each one pump stroke of hardener yields 0.8 fl oz of the exact 5:1 epoxy mix ratio. These durable polypropylene pumps provide years of dependable service.

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8.6

TotalBoat

TotalBoat 5:1 Marine Epoxy Resin Kit for Bonding, Filleting, Coating, and Laminating - Use for Fiberglass, Wood, Carbon Fiber, Boat Building, Repairs, Woodworking (Quart, Slow Hardener, Pumps)

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Main Highlights

High-Strength Marine Epoxy Resin Kits: System formulated for bonding, coating, and laminating. Build, repair, and restore boats, canoes, kayaks, SUPs, surfboards, RVs, and trailers. Stronger bonds and more durable than polyester fiberglass resin.
Ideal for Building and Repair Projects: TotalBoat marine epoxy bonds to wood, steel, lead, etched aluminum, fiberglass, carbon fiber, and other composites. Mixed viscosity and self-leveling properties ideal for wetting out fiberglass cloth.
Complete Epoxy Resin and Hardener Kit: Quart, gallon, and 4.5-gallon epoxy kits include resin, slow or fast hardener, color-coded pumps, and mixing supplies. At 75°F, pot life is 20 minutes for slow hardener, and 12 minutes for fast.
Compatible with Fillers: Use thickeners and additives to create epoxy fairing compound, filleting material, or gap-filling adhesives for boat building and repairs, carpentry, and woodworking projects. Compatible with other 5:1 epoxy resin systems.
Marine-Grade Formula: TotalBoat Traditional epoxy cures to a high-strength solid that can be sanded, shaped, and painted over. Resists chemicals, moisture, salt, and weather for long-lasting structural repairs. Not intended for clear coating.

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8.3

Bob Smith Industries

Bob Smith Industries BSI-205 Slow-Cure™ Epoxy - 4.5 oz. Combined, Clear - 30-Minute Working Time Adhesive for Wood, Fiberglass, Metal, Crafts & Structural Repairs

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Main Highlights

Extended Working Time: SLOW-CURE epoxy provides a generous 30-minute working window, allowing for careful positioning, alignment, and larger project applications.
Maximum Strength & Durability: Once fully cured, SLOW-CURE forms an exceptionally tough, impact-resistant bond - ideal for load-bearing or high-stress joints.
Multi-Surface Adhesion: Bonds securely to wood, fiberglass, metal, glass, ceramics, and most plastics, making it a versatile adhesive for hobby, DIY, and professional projects.
Excellent Gap-Filling Properties: Thicker formula is designed to fill gaps and bond uneven or porous surfaces with reliable hold and clarity.
Essential for Serious Builders: Perfect for boat repairs, structural applications, model building, and demanding craft projects - SLOW-CURE delivers lasting performance where strength matters most.

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8.1

West System

West System 209-SA Extra Slow Hardener

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Main Highlights

209 EXTRA SLOW HARDENER is a low-viscosity epoxy curing agent. It is useful in a majority of hot-weather bonding situations, and when very long working time and cure time are needed. 209 Extra Slow Hardener produces a slow epoxy cure that develops physical properties gradually at room temperature. It yields a rigid, high-strength moisture-vapor resistant and functionally waterproof solid.
USE WITH WEST SYSTEM 105 RESIN for general coating and bonding applications in extremely warm and/or humid conditions, and for extended working time at room temperature. Forms a clear, amber-colored solid with good physical properties and moisture resistance for bonding and coating applications.
PROVIDES ABOUT TWICE the working time of 206 Slow Hardener. 209's pot life at 72°F (22°C) is 40 to 50 minutes. Pot life at 95°F (35°C) is 15 to 20 minutes. Cures to a solid state at 72°F (22°C) in 20 to 24 hours. Cure to a solid state at 95°F (35°C) in 6 to 8 hours. Reaches maximum strength at 72°F in 4 to 9 days Minimum recommended working temperature is 70°F (21°C).
PAIR WITH WEST SYSTEM 105-A Epoxy Resin. Blend with with WEST SYSTEM 105 Epoxy Resin at a 3-parts resin to 1-part hardener ratio.
EASILY MODIFIED with WEST SYSTEM Fillers, Additives, and Pigments to suit the job at hand, whether coating, applying fiberglass, structural bonding, or fairing. Not intended for clear coating.

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8.1

West System

West System 105-B Epoxy Resin Bundle with 206-B Slow Epoxy Hardener and 300 Mini Pumps Epoxy Metering Pump Set, Pale Yellow

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Main Highlights

CONVENIENT EPOXY BUNDLE contains one can of WEST SYSTEM 105-B Resin (126.6 fl oz), WEST SYSTEM 206-B Slow Hardener (27.5 fl oz), and one set of calibrated 300 Mini Pumps. 206 Slow Hardener is a low-viscosity epoxy curing agent for use when extended working time or a longer cure time is needed. It also provides adequate working time at higher shop temperatures.
105 EPOXY RESIN is a clear, pale yellow, low-viscosity liquid epoxy resin. Blended with 206 Slow Hardener at a 5:1 ratio, it cures to a hard, solid plastic with superior physical properties. It will wet out and bond with wood fiber, fiberglass, reinforcing fabrics and a variety of metals. (206 Slow Hardener is not intended for clear coating.)
POT LIFE AT 72°F (22°C) is 20 to 25 minutes. Cures to a solid state in 10 to 15 hours. Cures to maximum strength in 1 to 4 days. Minimum recommended working temperature is 60°F (16°C). Does not contain VOCs and has relatively high flash point and no solvent odor, making it much friendlier to use than styrenated resins.
EXCELLENT FOR COATNG OR BONDING, this epoxy is easily modified with WEST SYSTEM fillers, pigments, and additives to suit an enormous variety of construction and repair projects, including fiberglass boat repair, strip kayak and canoe construction. Resin viscosity is approximately 1000 centipoise at 72°F (22°C)
INCLUDES CALIBRATED PUMPS that dispense 105 Resin & 206 Slow Hardener at the correct 5-part resin to 1-part hardener mix ratio. One pump stroke of resin for each one pump stroke of hardener yields 0.8 fl oz of the exact 5:1 epoxy mix ratio. These durable polypropylene pumps provide years of dependable service.

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Our Best Overall Choice

Best Choice

9.7

West System

West System 206-A Slow Hardener

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Editor's bottom line:

“This is the best one we tested. In terms of quality, brand and price, we couldn't ask for more.”

Main Highlights

206 SLOW HARDENER is a low-viscosity epoxy curing agent. It is useful in a majority of bonding situations, and when extended working time and cure time are needed.
MIX WITH WEST SYSTEM 105 Resin in a five-part resin to one-part hardener ratio. The resulting cured epoxy is a rigid, high-strength, moisture-resistant solid. The combination of 105 Resin/206 Slow Hardener has excellent bonding, coating and barrier coating properties.
CURES AT TEMPERATURES as low as 60°F (16°C). Will cure faster at warmer temperatures. Pot life at 72°F is 20 to 25 Minutes. Cures to a solid state in 10 to 15 hours. Cures to maximum strength in 1 to 4 days. Minimum recommended working temperature is 60°F (16°C).
PAIR WITH WEST SYSTEM 105-A Epoxy Resin. Blend with with WEST SYSTEM 105 Epoxy Resin at a 5-parts resin to 1-part hardener ratio.
EASILY MODIFIED with WEST SYSTEM Fillers, Additives, and Pigments to suit the job at hand, whether coating, applying fiberglass, structural bonding, or fairing. Not intended for clear coating.

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