Six reasons to use epoxy when repairing fiberglass boats

Six reasons to use epoxy when repairing fiberglass boats

Not sure if epoxy has what it takes to repair your fiberglass craft? “It’s versatile, strong, reliable and more than comparable to polyester resin,” says Hamish Cook, Technical Adviser at West System International. Fiberglass vessels like all other vessels are damaged. That is inevitable. Collisions and stranding damage the vessel with small notches as well as major damage to the structure. And longer-term problems such as osmosis and delamination can frustrate you out of the water as well. For many years, the automatic answer to many problems was to reach for polyester resin. But as the hulls become thinner, lighter and more flexible, they become harder to repair – especially with polyester resin. Step forward epoxy …

Epoxy is a great glue

One of the reasons that an epoxy product like WEST SYSTEM® Epoxy is useful for repairing fiberglass boats is that it is an incredibly effective adhesive. Creates a resistant bond to fiberglass, dried polyester laminates, wood and metals even if you use a thin layer. Polyester resin is difficult to compare with epoxy resin.

Epoxy is ideal for wetting glass cloth

If you’ve ever tried spreading cold butter on toast, you’ll know roughly what it’s like to moisten a glass cloth using polyester resin. You have to work hard to get an even, consistent layer – normally using a foam roller, brush or metal roller with spatulas. When you use epoxy, it’s like when you use hot butter, epoxy does the job for you. Brush the surface you want to moisten and the resin will fill as needed as the holes in the fabric. Which means less time working and more time eating toast.

Epoxy works well as a thin layer

Polyester resins are difficult to dry when exposed to air. So when used as a thin layer it stays sticky, because a higher percentage of the resin you use is exposed to air. As a result, it has limited use if you want to repair well-dried fiberglass laminates using only a thin layer. Epoxy does not have the same problem. It works as a resin for gluing, coating and laminating even though it is used as a thin layer – and is less likely to develop micro cracks.

Epoxy works at a variety of temperatures

Polyester resin manufacturers typically recommend using their products at temperatures of 15 ° C or higher, which can be a problem if your workplace temperature falls below the recommended one. Use the right hardeners in your epoxy compound, however – for example WEST SYSTEM 205 Fast Hardener® – you can work at temperatures as low as 5 ° C by following our guidelines for using epoxy in cold conditions. Epoxy also works well in high temperatures – with WEST SYSTEM 105 Epoxy Resin® and 209 Extra Slow Hardener® specially designed for extremely hot and humid conditions.

You can control how fast the epoxy dries

Using various hardeners – such as WEST SYSTEM 205, 206, 207 or 209 hardeners – you can adjust the drying speed of the epoxy, giving you more control over your work. Adding a catalyst such as MEKP (methyl ethyl keytone peroxide) to your polyester resin to adjust the drying time at cold temperatures creates a less effective bond. Epoxy shrinks less than polyester Polyester resin shrinks as it dries because styrene molecules evaporate. It’s a minor problem on smaller repairs, but if you’re repairing a large area it can cause you a big headache. Shrinking is stressful before you put your boat back in the water / sea, and that puts extra pressure on the glue. Epoxy shrinks much less. Therefore, the higher the repair, the more important it is to use epoxy. Still not sure which product is better for you? For expert advice on product selection, please email our technical team at:


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