Crazed Gelcoat prep and painting

[TrawlerTribe]

Trying to put together a plan to improve our topsides. It's an old boat with crazed gelcoat throughout. They are not caused from stress cracks and are all over the topsides. The boat has been painted previously and the paint is in rough shape. Thinking about learning to AwlGrip.
Can I sand, prime, and Awlgrip or do i need to Fair the entire topside to cover the crazing?
Wondering if the Awlgrip Primer will fill in the crazing and for how long or will it eventually bleed through the paint and show the cracks?
I have sanded a few areas through the white paint. There is an off white color underneath which i think is the actual Gelcoat. There are areas where the crazing is worse and they seem to have a white color. Wondering if it is old Fairing compound. If i sand through it it does down to glass mat.

Any advice in dealing with old gelcoat/Awlgrip appreciated.

Here is a pic if the crazing with no sanding and a pic of a section i sanded showing the off white color starting to show after sanding off the white paint.

A

 

[TDunn]

You do need to sand, fair and then prime before putting a high gloss top coat on. If you don't you will end up with the crazing showing in the paint unless you prime it very heavily (several times). I would suggest looking into Alexseal paint instead of Awlgrip. Alexseal is east to roll and tip and can be easily repaired and buffed, which is much harder to do with Awlgrip. You can repair and buff Awlcraft, but it is spray only application. Alexseal is also a two part polyurethane.

 

[mvweebles]

Recent extensive conversation on gelcoat repair recently on Cruisers Forum. Hopefully you can view the discussion. Some alternative approaches to full sanding. Not sure I agree with the comments but a worthy read for information.

http://www.cruisersforum.com/forums/showthread.php?t=226418

 

[TrawlerTribe]

Thanks..
I will look into Alexseal and read the shared thread link.
I've never painted Fiberglass so trying to come up with a game plan. There are areas where the crazing is so deep that if I sand too much it just falls apart and creates holes where i can see the glass mat underneath. I'm guessing i will need to chip out these areas until anything loose is out and apply something? Fairing compound or Epoxy? I filled a few old screw holes at the helm with an Epoxy product called Adtech that worked pretty well. Wondering if that would work.
Looking for the least amount of labor to prep and paint but without completely half assing it.
Is Sanding my best bet? What about paint removers? I've tried some 40 grit all the way to 320 grit and they work but slow and time consuming. If I start with 40 or 80 grit and work my way to 320 grit I can still visibly see the crazing but can barely feel it. Wondering if the primers will be enough to fill in the crazing cracks after sanding so I don't have to apply fairing to the entire topside.

 

[DDW]

In my experience if you do not sand below the cracks, the cracks will eventually print through the paint. You could cover with veiling cloth, but that will be a big fairing job.

Perhaps a gelcoat peeler is the quickest and most thorough solution. If it is really gelcoat, there is almost no chemical that will remove it.

 

[Larry M]

Alwgrip Top Coat and Axleseal are both 2 component polyurethanes. AwlCraft 2000 is a 2 component acrylic urethane and is not as hard as the polyurethanes but is easier to repair. Axleseal is a newer paint and the reviews are favorable from what I have read.

Hobo’s been painted twice, once with Awlgrip Top Coat and once with Awlcraft 2000. Both have their pluses and minus’s. The picture is after Awlcraft 2000.

As good as a paint is, it's only as good as the prep and the applicator. Good luck with your project.

Here’s a link for the application guide for Alwgrip’s products including discussions about prep and sandpaper.

https://specialtycoatings.brand.akzonobel.com/m/35d2b4ae2a5dee86/original/applic...

 

[RT Firefly]

Greetings,
We did our boat with Alexseal. VERY user friendly and there is an Alexseal fairing compound we used where necessary. Again, VERY easy to use. Mix 1:1, allow to harden and sand.
Personally I wouldn't sand to 320. I think Alexseal recommends to 180 IF I remember correctly.

 

[wwestman]

In my experience it is 95% prep and 5% final paint.

 

[Comodave]

You need to grind out each crack and fill them. Then sand and fair. I know it is an extraordinary amount of work but if you don’t the cracks will come back through the paint. Our boat had gel coat that was way too thick applied at the factory. In some areas it was an 1/8” thick so it cracked in many places. In some places I sanded all the gel coat off and faired it out. In other places I used a dremel tool and ground out the cracks, filled and faired it out. On the deck the nonskid had literally hundreds of cracks in the nonskid. I sanded off all the nonskid and used Kiwigrip to paint the deck. It will cover stress cracking. It has been over 3 years now and the Kiwigrip has held up wonderfully. It was a tremendous amount of work but our boat looks great now.

 

[localboy]

https://youtu.be/QtD0wvNAjD0

 

[TrawlerTribe]

Here are a few more pics of what I'm working with.
There is no way I can Dremel through these cracks. There are too many. It's not like the stress cracks where they are localized. These are disperesed throughout the topsides with millions of them.
I looked at the Alexseal and that seems up my alley. Like Awlgrip but more forgiving? They have multiple fairing products and primers. They recommend each be put on top of the other which could end up being way too many coats than I want to do. I Might try contacting Alexseal to see what they recommend for a DIY job that is somewhere in between spending the next 4 years on this project and just slapping some topcoat on.
Thanks for sharing the video....will watch now.

 

[RT Firefly]

Greetings,
Here's a WAG for those that have simply painted over their crazing only to have it reappear. Might it be the crazing was not cleaned well enough? Perhaps someone waxed the surface years ago and there was residual wax in the cracks causing poor adhesion?


Mr. TT. Picture #'s 1, 2 and 3: I would sand well with 180 but not necessarily eliminating the crazing. Wash REALLY well with a solvent recommended by Alexseal (As), prime, light sanding, re-prime where necessary then a finish coat (roll and tip). I see no reason, what-so-ever for the cracks to telegraph through other than contamination IN the crazing. If the substrate is clean, the paint WILL stick. That's what it's made for, after all. Might even take 2 coats of primer with sanding in between. So what? Much easier than fairing the whole boat. You're using the primer as a very thin fairing compound to fill the crazing.


In picture #'s 4 and 5, I would gently try to pry any loose gelcoat up then fair with compound, sand, prime and paint.


This isn't rocket science. By all means call As and get their opinion.

 

[Comodave]

Are these stress cracks just on the deck or are they on the cabin sides also? If they are just on the deck, I would sand the decks well and then paint with Kiwigrip and be done with it. Kiwigrip will cover those cracks and it wears very well. It is easy to apply and really tough. It is also easy to repair except it is hard to sand off. It is a latex paint so easy clean up.

 

[DDW]

Those are not stress cracks, they are shrinkage cracks from the gelcoat shrinking off the surface. Printing through the finish coat happens because all of the movement of the surface due to thermal and humidity concentrate at the crack lines, at the same time there is a stress riser in the paint there. If you have really flexible paint (like 2 part PU) it may not crack but the crack will print through and you will see it. Even fine cloth weave will print through. It may look OK for a couple of years, but I'll bet a six pack that you will see them eventually.

 

[Comodave]

I agree that the cracks will show through a 2 part poly paint, that is why I used Kiwigrip.

 

[SoWhat]

I have the exact same problem. The cracks go through the gel coat to the mat. They are a manufacturing issue. Too much catalyst, poor mixing ratio, curing in high humidity, who knows. I do know it is not economically viable to strip off the gel coat.

Any spot that has chipped and shows mat will have to be repaired. (For example the 2 pics that show your finger.) I went over my boat numerous times with a sharp blade and poked at any suspect spot.

My repair technique using West System:
1) Poke and prod anything suspect. Pick off any loose gel.
2) Dremel all spots that show mat. A wen 1/2" sander is very useful.
3) Clean spots with acetone.
4) Coat spots with catalyzed resin. Let dry to tacky
5) fair with resin and easily sandable microballons
6) Sand with 80 or 100. Might need a second fairing.
7)Clean again and apply 2 coats of thinned primer.
Now ready for your topcoat of choice.

I have finished the spot repairs, and sanded all of the gelcoat with 100 or 120. Planning on several coats of thinned primer, 2 or 3 coats of thinned topcoat in the spring. Haven't decided on paint, leaning towards a polyurethane.

Hardness and ease of touch up are issues. Trying to cover cracks, expense, and longevity lower on the list. If I can get 5 years then I'll be satisfied. (My experience with some prior spot repairs is 2 coats of primer will cover cracks for more than 2 years)