PRACTICAL Mixing the gloop – continued


s soon as the two-pack epoxy is mixed to the correct ratios with the right amount of copper powder added and well stirred in, the coating should be applied. Application should be by roller, not


7 The resin and hardener were mixed thoroughly before adding the powder.


Application – By roller, not brush A


brush. Using short-pile simulated mohair or high-quality neoprene foam sleeves is recommended: however, I found that the short-pile rollers I used shed some small fibres. Where they came off they could be seen in the coating, which was frustrating. If you try to remove them before the coats are cured you can end up taking off all the epoxy as well. I would recommend using decent foam rollers to be on the safe side. I found that as a water-based product, the


8 The pre-weighed powder in individual for each batch.


bags speeded up the mixing process


coating went on more smoothly and easily than a traditional epoxy coating, but during application it is important to keep mixing it to prevent the heavier copper particles settling out. This is especially the case when coating a boat upside down as the particles might sink away from the surface. I’m told this can happen on bigger boats at the top of rudders, for example: people sometimes find growth where they have applied it more thickly and more fluid has allowed more settlement. As I started, the first coat seemed patchy:


but it is important not to put it on too thickly because, like metallic paints, it can have a tendency to run. It is better to build up the antifouling layer in thinner coats, and with further coats I found the thickness built up nicely. I would wait until the coating felt almost dry before applying the next one, and as it turns out I didn’t get five coats out of the pack but just over four-and-a-half. When mixing the final coat, the ratios were amended accordingly by weight.


Cleaning up Before the epoxy has cured, equipment can be cleaned in warm water. However, don’t wash epoxy products into the water course or down drains. When cured it is an inert plastic, so trays and rollers can be disposed of in the normal way. Once the coats are all completed the


full cure takes place after five days, but the coating should apparently be cured sufficiently to launch after 72 hours at 20°C. As I was doing mine in the winter with colder temperatures I left it for seven days before moving the hull. When it was fully cured I then gave the hull surface a light burnish with a superfine Scotch-Brite pad to expose some copper.


9 The powder has to be thoroughly mixed with the epoxy resin. 1 When first applied it initially might look patchy, but don’t put it on too thickly.


2 Subsequent coats must go on as which was about an hour at 17°C.


soon as the previous coat has cured,


10 Each batch was thinned by 5% of


isopropanol, so 5g of it was added.


11 It is important to regularly stir the mix to stop settlement of the copper powder. 4


3 The copper-coated hull complete. When finally cured, the surface was lightly burnished with a superfine Scotch-Brite pad to expose some copper. Practical Boat Owner 585 April 2015 • www.pbo.co.uk


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