Cracking Paint

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Apr 20, 2019 | 06:43 PM

rllull

Thread Starter

3rd Gear

Joined: Aug 2016

Posts: 3

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Cracking Paint

I am in the process of having my 79 painted. We are having an issue where there are no visible cracks in the primer, but once we start to apply a second coat, cracks show up 24-36 hours later. This is happening in the roof between the T-tops and rear window. Any thoughts on a cause?

Apr 20, 2019 | 07:32 PM

cv67

Team Owner

Joined: Oct 2004

Posts: 81,241

Likes: 3,062

From: altered state

St. Jude Donor '05

Wow...bodyshop needs to figure this one out quick or pay someone else who knows whats going on. Keep us tuned in

Apr 20, 2019 | 07:55 PM

Skeetshooter

Advanced

Joined: Dec 2018

Posts: 83

Likes: 24

From: Ct

How much film is on it? The primer looks super thick.

Apr 20, 2019 | 08:48 PM

7T1vette

Team Owner

Joined: Jan 2006

Posts: 37,637

Likes: 3,112

From: Crossville TN

Gotta be a problem with the top coat paint or an incompatibility between the primer and top coat.

Apr 20, 2019 | 08:57 PM

fake

Safety Car

Joined: Jan 2004

Posts: 4,549

Likes: 343

From: Glastonbury CT

They have a glaze you can use to fill the cracks and it works . You are lucky it is the primer, not the base coat. I would fill the cracks and wait a week before i shot a base coat .

Apr 20, 2019 | 09:57 PM

71yellow454

Instructor

Joined: Apr 2006

Posts: 123

Likes: 103

From: Abingdon Maryland

What is under the primer? Was the car stripped down to bare fiberglass?

Apr 21, 2019 | 05:50 AM

rllull

Thread Starter

3rd Gear

Joined: Aug 2016

Posts: 3

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Yes, the car was taken back down to the fiberglass.

Apr 21, 2019 | 06:57 AM

PainfullySlow

Burning Brakes

Joined: Sep 2017

Posts: 1,219

Likes: 364

From: Tolland CT

Based on how deep that crack looks I would say there is WAY too much primer on it. IIRC primer shrinks a little while it cures which when applied in that thickness will cause cracking.

I am definitely no expert, I am just doing reading on this as I am about to begin the bodywork phase of my project but my understanding is that if you need that thickness of primer, you should be using filler to smooth everything out first and then apply MUCH thinner layers of primer.

Maybe Dub or one of the other experienced bodymen will chime in shortly.