West 655-8 G/Flex Thickened Epoxy Adhesive 3.9oz. Tubes

Why G/Flex 655 Thickened Epoxy Stands Apart

Standard marine epoxies are rigid and strong, but they can crack under repeated stress from wave impact, temperature swings, or engine vibration. Adhesive sealants flex well but lack structural strength. West System G/Flex 655 occupies the sweet spot between these two extremes — stiff enough to carry structural loads, yet flexible enough to absorb the dynamic stresses that boats endure every time they leave the dock.

With a modulus of elasticity of 150,000 psi, G/Flex can deflect further before breaking than conventional WEST SYSTEM 105/205 epoxy, making it particularly well-suited to joints between dissimilar materials that expand and contract at different rates.

Versatile Bonding for Difficult Substrates

G/Flex 655 excels where other adhesives struggle. Its toughened chemistry grips tenaciously to surfaces that are notoriously hard to bond, including oily tropical hardwoods, damp wood, polyethylene, ABS, aluminum, stainless steel, glass, and ceramics. For Canadian boaters working on everything from cedar-strip canoes to aluminum fishing boats, this versatility means one adhesive handles a wide range of repair and construction tasks.

• Bonds metals including aluminum and stainless steel
• Adheres to polyethylene and ABS plastics (with proper surface preparation)
• Grips oily tropical and domestic hardwoods
• Bonds fibreglass, glass, masonry, and ceramics
• Works on damp and difficult-to-bond wood surfaces

Easy 1:1 Mix Ratio and Gel Consistency

The G/Flex 655 comes pre-thickened to a gel-toothpaste consistency, which means it stays where you put it — on vertical surfaces, overhead joints, or in tight gaps. The 1:1 mix ratio by volume eliminates guesswork and reduces the chance of mixing errors that can compromise cure quality. Simply dispense equal amounts from each tube, mix thoroughly, and apply.

Working Time and Cure Schedule

At 22°C (72°F), G/Flex 655 provides 45 minutes of pot life and approximately 75 minutes of working time once applied. Initial cure occurs in 3 to 4 hours, with a workable cure reached in 7 to 10 hours. Full load-bearing strength develops in 24 hours. The minimum recommended application temperature is 4°C (40°F), making it suitable for early-season and late-season repairs in Canadian climates when temperatures are still cool.

Ideal for Canadian Marine Conditions

Canadian boats face unique challenges: freeze-thaw cycles, wide temperature swings between summer and winter storage, and the constant vibration of choppy Great Lakes or coastal waters. G/Flex 655's toughened formulation is engineered to handle these stresses without cracking or delaminating. Its waterproof cure and ability to bond at temperatures as low as 4°C make it practical for spring commissioning repairs when the workshop may not yet be fully heated.

Applications and Use Cases

G/Flex 655 is suitable for a broad range of marine repair and construction projects.

• Repairing cracks and damage on aluminum boat hulls
• Patching polyethylene and ABS canoes and kayaks
• Bonding hardware to fibreglass decks
• Laminating dissimilar materials (e.g., teak to fibreglass)
• Structural repairs to wooden spars, tillers, and trim
• Wetting out and bonding fibreglass tapes and fabrics
• Bonding keel joints and centreboard trunks subject to repeated impact

Specifications

• Product Code: C655-8
• Package Contents: 2 x 3.9 oz. tubes (8 fl. oz. / 250 mL total)
• Mix Ratio (by volume): 1:1
• Mix Ratio (by weight): 1.2:1
• Mix Viscosity (G/flex 655): Gel
• Pot Life (100g at 72°F / 22°C): 45 minutes
• Working Time: 75 minutes
• Initial Cure: 3 to 4 hours
• Workable Cure: 7 to 10 hours
• Full Cure: 24 hours
• Minimum Recommended Application Temperature: 40°F (4°C)
• Cured Specific Gravity: 1.11
• Cured Hardness (Shore D, ASTM D-2240): 75
• Compression Yield (ASTM D-695): 5,270 psi
• Tensile Strength (ASTM D-638): 3,440 psi
• Tensile Elongation (ASTM D-638): 32.7%
• Tensile Modulus (ASTM D-638): 1.44E+05 psi
• Flexural Strength (ASTM D-790): 5,190 psi
• Flexural Modulus (ASTM D-790): 1.56E+05 psi
• Heat Deflection Temperature (ASTM D-648): 127°F
• Onset of Tg (by DSC): 138°F
• Ultimate Tg: 154°F
• Part A Relative Density: 1.18
• Part B Relative Density: 0.99
• Part A Flash Point: > 200°F (93°C)
• Part B Flash Point: > 300°F (149°C)
• Storage Temperature Range: 40°F (4°C) to 120°F (49°C)

Key Features 

• Toughened epoxy formulation — absorbs shock, vibration, and thermal expansion without cracking
• Bonds dissimilar materials — joins metals, plastics, fibreglass, wood, and ceramics with a single adhesive
• Pre-thickened gel consistency — stays in place on vertical and overhead surfaces without sagging
• Simple 1:1 mix ratio — eliminates measuring errors and speeds up repair work
• Permanent waterproof bond — withstands continuous immersion and marine environments
• Works on damp wood — no need to wait for complete drying before bonding
• Usable in cool temperatures — apply at temperatures as low as 4°C for early-season Canadian repairs
• Extended working time — 75 minutes of open time allows careful positioning of parts
• More flexible than standard epoxy — deflects further before failure, ideal for dynamic marine loads
• Compatible with fibreglass fabrics — can wet out and bond glass tapes for structural reinforcement
• Long shelf life — remains usable for years with proper sealed storage