Can I put bottom paint over West System Epoxy ?

[OldManMirage]

So I had to sand down my rudder pretty good and I have a few spots that I will use thickened epoxy on.

My question is can I put bottom paint over West System Epoxy ?

I'd like to just go ahead and put a coat of un-thickened epoxy over the whole rudder as a barrier coat before bottom painting.

Is it acceptable to use this way ?

[Chotu]

Definitely doable, although some paint systems suggest the use of their primer on any surface to help with adhesion.

I did exactly what you’re saying below the waterline on my entire boat. However, I did use the primer, as Petit was suggesting at the time.

Held up great for many years. Still continues to hold.

[cr180]

Absolutely. BUT must first remove amine blush. Soap and water and a 3M scrub pad works well. And then sand with 80 grit.

[OldManMirage]

Originally Posted by cr180

Absolutely. BUT must first remove amine blush. Soap and water and a 3M scrub pad works well. And then sand with 80 grit.

I thought there was a step that I was missing. Sounds like a pain but I'll do it.

[Chotu]

Originally Posted by OldManMirage

I thought there was a step that I was missing. Sounds like a pain but I'll do it.

If you even have blush, it’s not a lot of work. It washes right off like some soap scum, but with less scrubbing. Easy stuff.

[Fishzine]

FYI, They make a barrier coat additive for West Systems epoxy. I have used it for a barrier coat for small sections under the water line. I keep it on hand since I always have some West Sytems Epoxy onboard.

https://www.westsystem.com/products/...coat-additive/

No idea how it compares between straight epoxy, but haven't had any problems using it

[Spot]

West warns against adding things to the water and solvents for removing amine blush:

"Amine blush, a byproduct of the epoxy curing process, may form under certain conditions. This waxy film is water-soluble, but many organic solvents are ineffective for removing it. That is why we suggest washing an epoxy surface with water (water clean enough to drink) using a Scotch-Brite™ pad (or wet sanding with waterproof wet/dry sandpaper) and drying it with paper towels before continuing with another operation. Soapy water, or water with ammonia or bleach, is not necessary and may leave its own residue, which is another possible surface contaminant."

Surface Preparation | WEST SYSTEM Epoxy

https://www.westsystem.com/instructi...e-preparation/