Wait time to paint over epoxy?

[Guest]

I know that is too general a question to have a single answer, and depends on the epoxy and hardener, cure temperature and humidity, fabric or surface epoxied, and potential amine blush or other outgassing.

I have topcoated too early, and paid the price sanding down my mess to start over. Since then I wait a week, or at least 4 – 5 days in warm, low humidity conditions, lightly sand, clean and topcoat. If it sands cleanly I take that as a good sign.

How long do other folks wait before topcoating with paint? Or varnish or spar urethane?

 

[memaquay]

That's about right, four or five days is usually what I wait.

 

[pblanc]

I have usually waited a couple of weeks, but I'm sure that is more than necessary. I think I picked that up from the instructions that came with a Pygmy wooden kayak kit suggesting to hold off for a couple of weeks before varnishing or painting the hull.

 

[stripperguy]

I once varnished a sailboat hull too soon after glassing the exterior
it was less than a week
it took me two weeks of scraping and sanding to recover
i now wait at least two weeks

 

[Guest]

Yeah, I don’t want to wait weeks plural. And I really don’t want to eff up by rushing the paint topcoat at this point either. I have eight newly installed skid plates I want to topcoat.

Four are now no-problem a week old, and four were just finished. All eight were installed with a mix of G/flex, West 105/206, graphite powder and black pigment. Heavy on the G/flex; at least two thirds G/flex to one third 105/206on the base coat, or ¾ to ¼ heavier still on the fabric saturating top coat.

All were compressed under peel ply, which should eliminate any potential amine blush (206 Slow hardener doesn’t blush like 205 Fast), and I’ll wet sand/scuff and clean the epoxied surfaces before the paint topcoat goes on in any case.

Observationally I think G/flex has a longer set up time than straight 105/206 (or 205), so at least 4 – 5 days in the warm, low-humidity shop.

I am planning on using black EZPoxy paint as the UV topcoat, and perhaps an epoxy paint over epoxy resin is less likely to gator up or fail to harden. I should probably put on my reading glasses and grab a magnifying glass to read the 0.25 font print on the EZPoxy can.

I’m just jonesing to put all four hulls side-by-side on sawhorses and have a day of taping, papering and EZPoxy painting. And then, more paint cure days later, move them all out and finally get my shop back to where I can make dust or work on other projects.

 

[dogbrain]

I think I read in the Raka epoxy directions to wait a week with their epoxy to sand and topcoat, so that's what I've done. I haven't had a problem so far.

Mark

 

[dougd]

Ahhh Grasshopper! Remember the old saying, "The proverb patience is a virtue means that it is a good quality to be able to tolerate something that takes a long time"! So Grasshopper, better to wait a little longer or take time to scrap off a virtual mess, I think I'd prefer to wait over scrapping!