WATCHING PAINT DRY!

[twodzusfittings]

I am repairing and painting my companion way hatch cover on my O'day 30. The original cracked in so many places, the balsa core got soaked and rotted to a mush. I cut away the interior panel, removed all the old core, replaced fresh core, finished with fiberglass and epoxy. Then turned it right side up, built the low spots with thickened epoxy, shaped and sanded, and lastly put a clear epoxy coat to seal it. Then I sanded the gel coat sides and applied interlux bright side with 10% thinner as my first coat on the prepped gel coat. It dried well. Sanded down and applied the same paint mix, this time painting the entire hatch cover. Where the second coat on the gel coat it has dried hard. But after a week of curing time, the filled and finished area is still tacky to the touch. What gives, anyone? Am I just impatient and it needs more time?


This is the upper side before after applying paint over the gel coat edges





This is how it looks with the whole top painted.

 

[Tally Ho]

How warm is it in your garage?

I was working with some epoxy over the winter a few years ago, and had a heck of a time getting my epoxy to kick over.

i finally had to add some heat to get things started.

I am sure paint is somewhat different, but if it was me, I would try some gentle heat (hair dryer or something) and see if that kick starts the paint. You are sure everything below the tacky area was really dry before you painted?

by the way, the hatch looks great! Nice work.

Greg

 

[twodzusfittings]

63 degrees. I just read your response, and thank you. To that I have started the indoor ceramic room heater at a low setting, at least to start with. I'll check it in eight hours. Thanks Greg.

 

[dlochner]

I suspect the epoxy is inhibiting the paint cure. Did you wash the epoxy before applying the Brightside? Epoxy forms an amine blush especially when when curing is cool environment. Sanding before removing the amine blush will grind it into the surface.

Call Interlux Tech support to verify.

 

[twodzusfittings]

Dave, thanks. You are an asset to the forum with your epoxy experience. So my epoxy was sanded and then wiped with Acetone. Paint was applied 30 minutes after the wipe down. Epoxy work has been cured for at least a month. I will reach out to Interlux as suggested.

 

[dlochner]

I think that's your error. The epoxy needs to be washed with warm soapy water and a scrubby, then rinsed. The amine blush is water soluble and waxy, acetone won't remove it. Usually when there are adhesion and curing issues it is the amine blush at the root of the problem.

If the paint hasn't cured by now, the first step in any solution will be removing the uncured paint. You'll need lots of paper towels and what ever solvent is used with Brightside. Fortunately you have a small area. The Interlux solvents tend to be pretty nasty smelling, a charcoal filter mask will help along with good ventilation.

 

[JBP-PA]

I'd get it warm for a while before you start over. I've had the same problem in cold conditions, especially with top coats. The underlying coats aren't fully cured and the top coats seem to take forever. Heat fixed me right up. Not hot, just warm.

 

[dlochner]

I'd get it warm for a while before you start over. I've had the same problem in cold conditions, especially with top coats. The underlying coats aren't fully cured and the top coats seem to take forever. Heat fixed me right up. Not hot, just warm.

The paint on the gelcoat areas cured, the paint on the epoxy areas did not cure. If heat were the issue, then none of the paint would have cured. The difference between the two areas is painting over gelcoat or a cured Brightside vs painting over plain epoxy. The usual culprit with paint or gelcoat not sticking to epoxy is in the preparation, specifically the amine blush. A second possibility is improper mixing of the epoxy, specifically not following the correct hardener/epoxy ratio. A third possibility is old epoxy which did not fully cure.

Be sure to remove the uncured paint with the right solvent. Solvents used for 2 part paints like Interlux Perfection will soften cured one part paints like Brightside.

 

[william24424]

Damn. That looks like a great project. Perhaps too much or too little catalyst? If you have time, more photos of the project, it's very satisfying to see a completed job for reference, and I was wondering if the teak had to be removed from the side of companionway? Thanks & good luck.

 

[twodzusfittings]

@ William 24424: The project started with cracked top issues.

I had broken teak railings/hold down sliders. I bought two new ones from Rudy. Then I removed the top and worked on it as in my opening work description.

What I left out was, I went on line and bought faux teak covering and applied. Two years later I was scraping it off. Sure it looked good, but the weather and the UV just disintergrated it.

Now I'm doing the topside again. Who said I can't keep myself busy? Ha ha. Running out of allowable space to upload pics. Will add more on the next post.

 

[twodzusfittings]

Pics of project continued.

UV and weather damage was all over the faux teak. This product was not SEADEK. The SEADEK product is closed cell and far superior Also $260 a 40x80 sheet.
So enough of this show and tell. Back to finding solutions. Another 7 hours of heated workshop time before checking the paint to see if there is any difference. Thanks all.

 

[dlochner]

Perhaps too much or too little catalyst?

Epoxy does not use catalyst. Polyester and Vinylester do use a catalyst. So what's the difference?

Epoxy resin and hardener undergo a chemical reaction where the two compounds join together to form the cured epoxy. If the prescribed ratio of hardener to resin is not followed, there will be incomplete curing with too much hardener or resin, usually resulting in a sticky mess that must be removed.

The catalyst in polyester resins stimulates and accelerates a naturally occurring process in the resin in which the molecules realign and harden into a solid mass. More catalyst speeds up the reaction, less catalyst slows it down. Over time the process of molecule realignment will happen by itself, that's why there is a very short shelf life for polyester resin and gelcoat (which is based on polyester resin). The process of curing polyester resin is more of a physical process rather than a chemical process, i.e., the combining of 2 different chemicals to form something new. In polyester resin the catalyst does not become part of the resin.

This of course is the layman's version, which is mostly correct. Our resident chemists, @rgranger and @thinwater could give a much more detailed explanation.

 

[twodzusfittings]

Thanks Dave. Great education. I agree with your assessment that it is not a heat/temp issue. The amine blush scenario sounds so plausible to me, it's the direction I'm heading with. I cannot use any chemical paint removers at the present as it will stink the whole house and the admiral will have my head on a platter, so I will wait until a weather window comes along to let me work outside, wiping off the paint. It's actually weird, the interlux brightside doesn't give off any strong odors. I painted the whole thing and the admiral didn't smell a thing.

 

[twodzusfittings]

Huh! Where there's a will there's a way. Opened up the workshop back door, pulled my work table to the door, used lacquer thinner to wash off the tacky paint. It did not affect the painted gel coat. All clean now. Cleaned up my shop while the few remaining fumes escaped out the door, put the work table back and all the products needed to continue with the project, like an OR room Mayo stand. Now I wait to wash with soap and water and a scotch brite pad.

 

[dlochner]

Before painting the whole hatch, try painting just a few square inches. If it still doesn't cure, you'll have a smaller mess to clean up.

 

[BigEasy]

Now I wait to wash with soap and water and a scotch brite pad.

Have the same problem with a fixed sea hood that covers a cast acrylic companionway slider. The seahood developed a leak, probably where the factory installed a dorade vent, causing the balsa core to rot. The deck side is finished with nonskid. Going to use core cell for new core. How many layers of cloth did you use over your new core? Plan to spray gelcoat over the nonskid to refresh & cover some spider cracks.
Your workmanship looks great! When you redo, perhaps a heat lamp suspended over the hatch will help with curing.

 

[twodzusfittings]

Thanks for Layer of cloth fine weave first. Then installed PVC core and filled gaps with epoxy resin. After cure, I used a large weave roving.

 

[twodzusfittings]

@dlochner et al. I took the opportunity to set up saw horses outside in this 34 degree weather and with hot water, kitchen soap and a scotchbrite cloth, scrubbed every which direction. After 30 minutes of rigorous scrubbing, I rinsed off the top. Oh my, that nice shiny finish has been replaced with a very dull surface. I think I got it all. I wiped it down with paper towels and then brought it inside to dry. I will let it dry for two days, check with feel and look for any missed areas, then as suggested, apply paint to a small area to see if it cures. I'm learning a lot about epoxy work and starting to get the hang of it. Maybe a hard dodger with a soft canvas top may be a future project. Who knows, let's get this one finished first, but you can't blame a guy for dreaming.

 

[dlochner]

Oh my, that nice shiny finish has been replaced with a very dull surface.

That nice shiny finish was the amine blush.

 

[twodzusfittings]

After a quick sand and final cleaning I painted the whole hatch cover again, using a mix of paint and 10% paint thinner. It went on so well and after much rolling in all directions here is the still wet look result. This just the first coat. I intend to do one more coat with 5% thinner and then the final coat straight paint.