Ok, I’ve googled this topic and seen a number of replies on both sides of the argument. I’m planning to paint the inside of my Pocketship with Interlux Toplac. The Interlux site is somewhat vague on whether priming is required. I understand that priming helps to eliminate small imperfections. I probable will prime the large areas - they will be easy to prime and more importantly to sand.
Anyway - is priming a nice to do, or a Must Do?
I’ve done it both ways. Both ways the boats floated (still do), both ways looked about the same initially and after a couple of months of use they looked identical.
On the primed boats I used high-build primer. In my opinion the horror stories about it sucking water out of the air are very much exaggerated, but that could have been luck on my part, painting when we had low humidity.
On the unprimed boats I was painting over fairing compound made of epoxy and phenolic microballoons. I had sanded to #220 with a fairing board. That had pretty much gotten rid of any pinholes and such.
As far as the paint sticking, all three products - epoxy, primer and paint - were made by System Three and guaranteed compatible. That’s why the paint stuck to the fairing compound even without primer.
So, to sum it all up, based on personal experience, I don’t see a need for primer as long as the surface is epoxy encapsulated, has had a diligent course of fairing and sanding and all the finish products are guaranteed compatible. Primer seems most valuable to me on bare wood. I’ve stopped using it on epoxy-encapsulated builds anymore.
Laszlo
I understand your frustration, I had the same issues with my first build. I even called up CLC and was told adamantly to prime. I went on the conservative side and primed the interior. I even used epoxy/microballons over most of the surface and sanded that to a 220 finish before applying the primer. Then I sanded about 90% or more of the primer off. It was a lot of unnecessary work. There were a few areas that needed minor fairing and on those areas I used glazing putty. Apply the putty on with a rubber squeegee using as little as possible wait an hour or so and sand. It’s great for really small swirl marks and no mixing or wasted epoxy
For the exterior of the hull I used Toplac Plus with no primer. I rolled and tipped the first two coats out of habit. Then I just rolled only as suggested and got as good or better results. Not having to tip takes half the time making keeping a wet edge easier.Keep the roller evenly saturated throughout and use light stands to get the best lighting as possible.