Copper epoxy antifoul, Starboard Hull

Chocolate Coated Bum

Posted by Paul

I pumped 10 pumps of resin directly into the roller tray and mixed it with the drill and mixer attachment. After about a minute of mixing I poured in 500g of copper powder and mixed for another minute before rolling it onto the hull. On the port hull I used a medium pile roller for the first coat and a fine foam roller for the second coat. I used foam rollers on both coats on the starboard hull and in retrospect using the medium pile roller was a better choice for the first coat. The reason is that there are still pinholes here and there in the sanded finish of the highbuild and the coarser roller more effectively filled these pinholes. I left a coarser finish that was somewhat reduced by the fine rolled second coat. The fine roller on both coats has left a smoother finish but has left a few pinholes that I have to now touch up. I am not too concerned as there is another coat of antifoul going on that will fill these but if I were leaving it at this stage I might be concerned enough to give it another coat.

One of the things that the copper epoxy coat does is that whilst it is wet it is glossy and because it is a dark color it highlights any discrepancy in the fairness of the finish. But this is only of benefit if you have done a good job because there is a lot of work to fix it now that the copper coat is on. It would involve a lot of sanding to remove the coat, re bogging, re sanding to fair and then re applying the copper coat. This area is underwater so I doubt you would go to this extreme even if the finish was very poor. Fortunately I have done a reasonable job of fairing and I am happy with it.

I waited 3 hours before starting the second coat. The first coat was still very tacky, if I touched it I left my finger prints. It is always a difficult question of how long to wait to apply the next coat. If the resin is set the bond is no longer going to be a chemical one and without sanding not a very good mechanical one either. In the summer months half an hour to an hour after the first coat would be fine. Whilst there have been some summer like days it is still spring weather and today was only about 20c. My concern was that perhaps the thick copper rich coat would be too difficult to apply onto a still tacky surface. There is no technical issue in applying the second coat before the first is sufficiently dry except it is hard to apply as the roller tends to stick. This was not a problem so the first coat was sufficiently dry or the second sufficiently wet to roll on easily.

As per the first hull I used 2 lots of 10 pumps (490g) each with 1 kg of copper powder and I lot of 5 pumps with 500g copper so around 67% by volume and this was an almost exact amount to cover the entire underwater area plus just a little left over which I used to touch up the first hull in places I had scratched whilst rolling it over.

So with the second coat on, all I will do tomorrow is to remove the skirt and check the finish. I could start to remove the temp bulkheads, and get started on the internal tapes but I think I will have another lazy Sunday.

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