Trade Secrets: Using epoxy to repair barrier coating

An epoxy barrier coating protects your boat from moisture and gives you a smooth, stable base which will help secure the finishing coat to protect your boat from sun damage when you’re out and about. So what’s the best way to restore this coating after it’s been damaged?

Before starting the application, prepare your surfaces for bonding by carrying out local fairing on the area you’d like to protect. It’s best to begin your coating within 24 hours of final sanding as this will help to avoid the possibility of surface contamination. Once this has been done, simply follow these four simple steps to protect your surfaces.

Preparing the epoxy mixture

Start by mixing small amounts of resin/hardener at a time – an opaque finish WEST SYSTEM 105 Epoxy Resin® and 205 Fast Hardener® or 206 Slow Hardener® will produce a high quality, protective coat. Next pour the mixture into a roller pan and load up your roller with a reasonable amount of the epoxy mixture, squeezing the excess out on the roller pan to make sure the roller is evenly coated. Using disposable, thin urethane foam rollers, such as roller covers, will give you great control over film thickness, leave less stipple than thicker nap-type roller covers and will stop the epoxy from building up and curing as quickly on the cover.

Applying the epoxy

First, roll the epoxy lightly and randomly over a small area – approximately 600mm x 600mm – spreading it into a thin smooth film. You may need to increase pressure slightly as the roller dries out but try not to roll too vigorously, as this may work air into the coating. Use long, light and even strokes to reduce roller marks, then overlap the previously coated area to blend it all together. Finish each batch by dragging a roller cover brush lightly over the surface with enough pressure to smooth the area and remove air bubbles. Then, overlap and blend in the edge of the previous batch allowing the film thickness to become smooth. Now you’ll be ready to apply your next coat.

Re-coating

Repeat steps one and two to apply your next coats of epoxy. Make sure the previous coat has cured firmly enough to support the weight of the next coat. The best time to re-coat is when you can leave a finger print in the previous coat, without leaving any residue on your hand. Apply each coat in the opposite direction to the previous coat (e.g. first coat vertical, second horizontal, third vertical). To protect the outside surfaces of your boat effectively, you’ll want to apply a minimum of three coats (approx. 300 microns) of epoxy and at least six coats for those areas below the waterline.

Preparing for the final finish