Fixing Bad Crazing

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
mcamuso
Posts: 21
Joined: Tue Jun 15, 2021 10:40 am

Fixing Bad Crazing

Postby mcamuso » Wed Oct 27, 2021 2:16 pm

My 1983 15 Center Console boat interior has bad crazing throughout.

Q1: can media-blasting be used to remove all the gel coat and new gel coat resin be applied in the interior?

While the upfront costs would be higher, the labor costs should be lower.

I fear that, if I bring out each one then once I’m done painting, crazing will start up again.

dtmackey
Posts: 571
Joined: Thu Sep 28, 2017 9:29 pm

Re: Fixing Bad Crazing

Postby dtmackey » Wed Oct 27, 2021 3:11 pm

Media blasting and maintaining a uniform surface isn't exactly each. You will bne leveling the surface before gelcoating. I spent a day with a die grinder in my 15' on miles of crazing, then filled, sanded, epoxy primer and Awlgrip. I'd do it the same way again.

I've media blasted boats before, both wet and dry and find that wet tends to provide a better surface prep, not to mention the water keeps the surface cool and helps damped the impact of the media, which I used recyled glass since the profile is better for surface prep on gelcoat.

My wetblast setup is 3600psi at 4GPM with a media injection before the discharge nozzle and I'm pleased with it.

My dry media blast is 120 - 150psi at 15CFM, but the discharge tip has a much smaller radius so the are you are working is smaller and more prone to removing too much material on gelcoat. Dry media can also create excessive surface temps.

D-

mcamuso
Posts: 21
Joined: Tue Jun 15, 2021 10:40 am

Re: Fixing Bad Crazing

Postby mcamuso » Wed Oct 27, 2021 3:23 pm

Got it.

I read all your posts about doing [refurbishing your 15-footer]. I internally curse you as [your posts about refurbishing your 15-footer] pushed me to[buy and try to restore ] a 15-footer, myself.

Q2: Has any [gel coat ] crazing [reappeared] on your 15-footer since its refurbishment?

dtmackey
Posts: 571
Joined: Thu Sep 28, 2017 9:29 pm

Re: Fixing Bad Crazing

Postby dtmackey » Thu Oct 28, 2021 11:10 am

Putting paint over crazing won't fix the unlying problem. Using high-build primers may minimize the visual appearance, but over time the crazing will come through the paint. There is no quick fix.

D-

mcamuso
Posts: 21
Joined: Tue Jun 15, 2021 10:40 am

Re: Fixing Bad Crazing

Postby mcamuso » Mon Nov 01, 2021 10:39 pm

dtmackey wrote:Putting paint over crazing won't fix the unlying problem. Using high-build primers may minimize the visual appearance, but over time the crazing will come through the paint. There is no quick fix.


I know.

I plan to spend plenty of time grinding and filling.

Q3: Once [the preparation and painting are] done, will the all-over crazing start again?

jimh
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Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
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Re: Fixing Bad Crazing

Postby jimh » Tue Nov 02, 2021 8:04 am

The reason for crazing to appear is generally thought to be due to poor care and exposure to sun and weather. The gel coat resin needs to be kept from becoming too dry and shrinking. Dry and sun-baked gel coat resin becomes brittle. It cracks apart. There is even some advice to rub an oil (Coconut Oil has been mentioned) into the gel coat to keep it from drying out.

The problem with that method: paint applied over recently-oiled gel coat probably won't adhere very well.