Painting over crazed gelcoat

[Brooksie]

Anyone have any experience applying topside paint (2pk) over crazed gelcoat?
[FONT=&quot]Getting ready to paint my 35’ 45yo boat still with it’s original gelcoat using Perfection which I have had great luck with on past projects. Now comes my own boat and on one side of the hull topside there is a 6’ section from W/L to gunnel that is crazed. It has never been hit there and it is not spider cracking. A tape test (blue masking) pulls up a few tiny particles but no flakes. Of course there is dirt and wax in the cracks I would assume..
Questions: Is a washing, solvent wash, 36 sanding, and epoxy priming going to do the trick in this area? Or coating with epoxy b/4 priming? Or must this area of gelcoat be completely removed first?
[/FONT]

 

[rslifkin]

Could you potentially just sand it down until there's no more visible crazing? I'd think after 45 years and probably a few rounds of polishing that it can't be so thick as to be a problem to sand through.

 

[Comodave]

If there is any cracks it will show through the 2 part paint. The paint doesn’t hide any imperfections. Also if blue tape pulls pieces of gel coat off then the 2 part paint will not have a good foundation, so to speak, under it and it will end up coming off with the gel coat. You need to get rid of all the loose gel coat and repair the surface before painting. I had areas that I had to remove the gel coat completely and fair it out before painting. Remember that about 90% of the work is before you start to apply the paint.

 

[STB]

It needs to be sanded until the cracks are gone or almost gone. If you sand them completely out, prime and paint as normal.

If you get them to where they just barely, barely catch your fingernail, prime a coat or two, sand again, and then they should be gone. If any areas are bare of primer after danding, prime again before painting. Otherwise paint again.

The easiest thing to do is just to sand until they are gone. Even if you sand through the gel it isn't a problem. Prime twice and paint.

 

[mvweebles]

Folks - Brooksie owns a sistership to my 1970 Willard 36. He has hull-strakes molded into the gelcoat and I'm guessing he wants to be careful not to lose them. There was an extensive thread on CruisersForum that was only mildy interesting with a ton of the usual guesswork speculation. One person had an interesting suggestion that might be worth a test - use superglue in the cracks to seal and fill. It sounds crazy to me, but it's a $3 effort and if it doesn't work, not out much effort. Link to thread below.

For Weebles, my W36, her paint job was almost complete when Covid hit and closed the yard in Ensenada. I had some crazing from standing water, and a few areas where the gelcoat just washed away over time. Ton of hi-build primer used on her.

https://www.cruisersforum.com/forums/f55/gelcoat-vs-paint-226718.html

 

[cool beans]

I've done plenty of body work on cars, and having a solid foundation makes for a great and long lasting paint job

My guess is that over the years, moisture has wicked it's way into one crack...which freezes and expands in the winter...allows more moisture to collect, etc. Same reason behind concrete spalling.

For the effort and cost to paint your boat, sand down the gelcoat to glass, seal with epoxy, and fair it back out. The shiny finish of your paint job is only as good as the substrate it's painted on

 

[Moonfish]

I've had to do this a few times, paint over crazed gelcoat. I've used a couple of methods and both worked great. One is to use the 2-part Evercoat polyester glazing putty, the other is epoxy. I ran out of hardener one time for the putty, so I ended up trying the epoxy. Worked just as well as the filler putty. Although being clear, it was a little harder to see where I had been.

The other thing I learned is that sometimes you need to take a couple passes at the cracks. Specifically, I had spider cracks. After applying the filler or epoxy you then sand smooth. Like someone said, take your fingernail and if you can catch an edge, you know the paint will not fill it. Typically, one more run at filling will do the trick. Though in one area where there was blunt force damage, I had to do four applications to finally fill all the cracks!

 

[Brooksie]

I've had to do this a few times, paint over crazed gelcoat. I've used a couple of methods and both worked great. One is to use the 2-part Evercoat polyester glazing putty, the other is epoxy. I ran out of hardener one time for the putty, so I ended up trying the epoxy. Worked just as well as the filler putty. Although being clear, it was a little harder to see where I had been.

The other thing I learned is that sometimes you need to take a couple passes at the cracks. Specifically, I had spider cracks. After applying the filler or epoxy you then sand smooth. Like someone said, take your fingernail and if you can catch an edge, you know the paint will not fill it. Typically, one more run at filling will do the trick. Though in one area where there was blunt force damage, I had to do four applications to finally fill all the cracks!

So did the section you did with epoxy stand up over time?? That was what I was thinking of doing after heavy 36 sanding, epoxy roll and squeegee, sand 80, epoxy again, then epoxy primer, then paint.

 

[Brooksie]

I've done plenty of body work on cars, and having a solid foundation makes for a great and long lasting paint job

My guess is that over the years, moisture has wicked it's way into one crack...which freezes and expands in the winter...allows more moisture to collect, etc. Same reason behind concrete spalling.

For the effort and cost to paint your boat, sand down the gelcoat to glass, seal with epoxy, and fair it back out. The shiny finish of your paint job is only as good as the substrate it's painted on

I'm sure you are right and peeling the gelcoat and installing a new, more flexible epoxy base is the best way. I don't want to buy a peeler and I'm not that good with a disc grinder, and it is thick (that's likely why it crazed in the first place. Of course I would heavily sand it and hope to bridge the craze with epoxy maybe even West Gflex.

 

[Moonfish]

So did the section you did with epoxy stand up over time?? That was what I was thinking of doing after heavy 36 sanding, epoxy roll and squeegee, sand 80, epoxy again, then epoxy primer, then paint.

The parts I did with epoxy were done last spring/summer. They look great as of now. No sign of crazing or cracks under the paint.

The 2-part filler putty I did many years ago and it still looks good. But I think I'll stick with the epoxy moving forward, as it has a much longer pot life which allows covering more problem areas in one application.

 

[Comodave]

Our boat has really thick gel coat in places and therefore had a lot of stress cracking as a result. One area the gel coat was about an 1/8” thick. I literally ended up using my belt sander with 40 grit and removed all the gel coat. Then multiple coats of polyester filler and lots of long board sanding. Some other areas had cracks but were not as bad so I took a dremel tool and ground each crack and then used the poly filler (3M Premium). Then sanded and filled until it was smooth. Worked well. The decks had hundreds of stress cracks throughout the nonskid. The nonskid was a tiny diamond plate pattern and almost impossible to repair. So I sanded all the nonskid off and painted the deck with Kiwigrip. Kiwigrip nonskid is wonderful stuff. But it is really tough and if you have to repair an area painted with it, hang on, belt sander with 40 grit time. Just remember that almost all your time goes into prep not the actual painting. I had a professional painter come in and spray the hull. He came the first time I thought that I was ready to paint. From 15’ away he said give it another 2 weeks prep and then we will paint it...

 

[grahamdouglass]

What type of epoxy to use

There are many types of expoxies out there. On the one hand you need an epoxy that will seep into the spider cracks. This would be a very thin epoxy like SYSTEM THREE S1 PENETRATING EPOXY SEALER. Would using an epoxy like this sealer, which is very thin with low viscosity be one way of filling spider cracks?
Would cleaning, sanding with a 60 grit, applying the sealer and sanding. Then several two part epoxy paints like perfection under coat, each sanded and repainted to build up a layer of base work? So then you would use a final coat of gloss perfection?

 

[Cigatoo]

Brooksie
If you call Joe out at Mertons in Springfield he will fix you up with what you need. You will have it o night via UPS. Either his own stuff or System 3. Or ride out there. Great guy to deal with.
Merton's Fiberglass & Marine Supply

 

[FF]

"I've done plenty of body work on cars, and having a solid foundation makes for a great and long lasting paint job."

So before attempting to paint the cracks which come from a local overload , the underside of the cracked area must be reinforced / repaired .

Just filling the cracks will not solve the underlying problem.

 

[Pete Meisinger]

I'm no expert. I did paint my Albin with pretty good results. The key is to get the old finish CLEAN. The TSP substitute you buy in hardware stores is no good. Buy real TSP online and get the boat clean.

I used the roll and tip method and am happy with the job. It is not perfect but then again it was not $15,000.

pete