G/flex Epoxy Adhesive 655-8, two 4.5 fl oz. - Flexible Waterproof

In this review the focus is on the G/flex Epoxy Adhesive 655-8, a two-part, toughened epoxy supplied as two 4.5 fl oz. cartridges. The bottom line: this is a repair-grade adhesive for hobbyists and tradespeople who need a waterproof, structural bond on hard-to-bond substrates. It earns recommendation mainly for its exceptional adhesion and flexibility versus standard epoxies, making it especially useful for bonding dissimilar materials and for repairs where movement, vibration, or damp conditions are expected.

Key Features

• Excellent adhesion: Bonds reliably to difficult woods, metals, plastics, glass, and fiberglass for permanent repairs and assemblies.
• Toughened flexibility: More flexible than conventional epoxies so joints can absorb expansion, contraction, shock, and vibration without cracking.
• Waterproof performance: Suitable for damp surfaces and can be applied under specific techniques even underwater for boat and marine repairs.
• Two-part 1:1 mix: Simple equal-ratio mixing with a predictable 46-minute pot life at 72F and a 60-75 minute open working time.
• Practical cure schedule: Initial cure in 3-4 hours, workable cure in 7-10 hours and full cure in 24 hours for fast turnarounds on repairs.

Who It's For

This epoxy is best for boat owners, woodworkers and repair technicians who need a structural, waterproof adhesive that can join dissimilar materials such as aluminum to fiberglass or polyethylene to fiberglass. It suits DIYers fixing rotomolded kayaks, canoe owners working with polyethylene or ABS, and fabricators who require a tougher, slightly flexible bond.

Those who should look elsewhere include users who require an ultra-fast setting adhesive for instant joins, or those needing a high-temperature structural epoxy for continuous exposure above typical ambient conditions; in those cases specialized formulations or adhesives are more appropriate.

Pros & Cons

Pros

• Tenacious adhesion to metals, plastics, glass, masonry and fiberglass for reliable repairs.
• Flexibility that allows bonded parts to move with thermal expansion, shock and vibration.
• Thickened consistency that stays in place around joints and can wet out fiberglass tapes and fabrics.

Cons

• Pot life of about 46 minutes requires planning for larger assemblies and may limit very fast production work.

Specifications

Our Verdict

G/flex 655-8 is a practical, value-packed epoxy for repairs and joins where adhesion to difficult materials and some flexibility are essential. It is a good investment for boat owners, repairers of plastic craft, and anyone bonding dissimilar substrates, offering waterproof structural bonds and an accessible cure schedule for weekend and workshop projects.

Frequently Asked Questions

Can G/flex bond to polyethylene or ABS?
Yes, it is formulated to bond rotomolded polyethylene and ABS when proper surface preparation is used and is commonly used for kayak and canoe repairs.

Is G/flex waterproof?
Yes, it creates permanent waterproof bonds and can be used on damp surfaces and in certain underwater repairs with correct technique.

How long do I have to work with a mixed batch?
The mixed pot life is about 46 minutes at 72F with an open working time of roughly 60-75 minutes, so plan and pre-fit parts before mixing.