G/flex 650 Toughened Epoxy by West System

4/5 · 1 review
from $39.95
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on orders over $90
Quebec, Ontario · More info

G/flex 650 is a toughened, versatile, liquid epoxy for permanent waterproof bonding of fiberglass, ceramics, metals, plastics, damp and difficult-to-bond woods.

With a modulus of elasticity of 150,000 PSI, it is a bit more flexible than standard epoxies and polyester, but much stiffer than adhesive sealants. This gives it the ability to make structural bonds that can absorb the stress of expansion, contraction, shock, and vibration.

It is ideal for bonding dissimilar materials. It can be modified with WEST SYSTEM fillers and additives and used to wet-out fiberglass tapes and fabrics.

Benefits of G/flex 650 Toughened Epoxy

A toughened epoxy that’s flexible

G/flex has been toughened. This gives it the ability to make structural bonds that can absorb the stresses of expansion, contraction, shock, and vibration. This epoxy is resilient and impact resistant. With a modulus of elasticity of 150,000 psi (WEST SYSTEM 105 Resin/205 Hardener has a modulus of elasticity of 450,000 psi), G/flex is more flexible and can deflect further before breaking than WEST SYSTEM 105/205, while being much stiffer than typical adhesive sealants.

Adhesion to wet and damp surfaces

G/flex has the ability to glue damp woods. It can be used on wet surfaces, even underwater when applied with specific techniques.

Excellent adhesion to hard-to-bond woods

G/flex adheres tenaciously to difficult- to-glue hardwoods, both tropical and domestic varieties. This is important since many of the exotic and tropical species now being used to replace traditional woods present bonding challenges.

This toughened epoxy bonds well to many materials

G/flex is ideal for bonding a variety of materials, including dissimilar ones. It has has a superior grip so that it can be used to bond to metals, plastics, glass, masonry, and fiberglass. This epoxy is ideal for repairs to aluminum boats and polyethylene and ABS canoes and kayaks. It can also be used to wet out and bond fiberglass tapes and fabrics.

Easy-to-use toughened epoxy

G/flex is a simple two-part epoxy system. Resin and hardener are mixed in a 1-to-1 mix ratio by volume. It provides a relatively long open working time, yet it cures quickly and can be used in cool temperatures. Because it is simple to mix and use, this 2-part epoxy is an excellent starting point for customers new to epoxy use.


G/flex can be modified with WEST SYSTEM fillers and additives if you need to meet particular bonding needs. Adding G/flex to other WEST SYSTEM epoxies can improve their toughness and flexibility.


8 oz (236 ml)
$39.95 In stock
32 oz (946 ml)
$124.95 In stock


Classification Epoxy Resins for Wood
Wood Glues
Brand West System
  • 8 oz (236 ml)
  • 32 oz (946 ml)
Sold Since December 9, 2020
Drying Time
  • Pot Life: 45 minutes
  • Working Time: 75 minutes
  • Get Time: 3-4 hours
  • Cure Time: 7-10 hours

Times are based off a 72°F (22°C) ambient temperature. Cure times are faster at higher temperature and in thicker application.



Mix Ratio


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Easy to work with

Doug Tompsett · May 18, 2021 · edited August 11, 2021

I recently purchased this from Ardec to repair leaky rivets on my aluminum boat. Shipping was fast.

Revised to 4 stars
Followup; After allowing many weeks to cure (like 2 months, because I was too busy to go boating), I finally got in the water, and had several rivets still leaking. Disappointed as I followed all instructions and had the ideal setup with the boat upside down, easy to clean/prep/apply. Had to patch the worst offenders from the inside before a trip, and will need to redo several more. Reached out to West for their recommendations for repairs.


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