cracking paint?

[timaishu]

Hi guys, its many many years since I was last present on here. I have a 93 firebird formula that was resprayed in 2002-2003. Prior owner garage kept it, I bought it two years ago and it lives outdoors. The paint had defects like this when I got it, but I feel there are more of them now. What exactly is going on here? I know most of the panels on my car are SMC which is composite (sheet molded compound). I wonder if this has to do with it, maybe the material moves with age cracking the paint? The paint still shines and the marks are only noticeable up close. Three feet away its not noticeable at all.

https://i.imgur.com/SVVawZW.jpg
https://i.imgur.com/REObpVa.jpg
https://i.imgur.com/bPK6udE.jpg
https://i.imgur.com/nIaSlfc.jpg

[57Rambler]

Modern paints do not require a flex agent for plastic parts, so my only guess would be that whoever painted the SMC panels/parts did not use an adhesion promoter.

[SWETM]

Just to clarify. Is the repainted parts base color coat and then clearcoat or single stage paint?

57Rambler is that's so with all of the base color coat/clearcoats systems that they don't need the flex agent?
Is it usual from the lower end paint jobs that they skip the primer when repainting. I see on many american classic cars that's restored and then imported here to Sweden. That they starting to flake the paint and you see no trace of a primer of any kind. And adhesion promoter is like a primer coat? Or is it a primer needed to be used on plastic panels with this adhesion promoter in it?
Think I have seen you post before on paint questions. So is just interested personally about it if you the knowledge about it.

Something seems to be going on with the base color coat or if it's something under the SS paint layer.

/ Tony

[FUNX650]

IMO:

•Looks like: Checking/Crazing.
-There can be several underlying causes.
-Not much that “Detailing” can do at this
time to completely remedy this situation.

:idea:
Although the actual repair of this type of paint
defect will require a re-paint...its inevitable pro-
gression towards ‘paint failure’ may be somewhat
slowed through prudent applications of a Glaze,
followed by a Sealant (most Waxes will leave an
unwanted white residue in the cracks).



Bob

[Mike Phillips]

Seen a lot of this in my life, for maintenance, I still machine polish over it just be gentle.

Living in San Diego - could be the expansion and contraction of the panels over time that caused the paint to crack like you see. Paint quality/type probably a factor too.

How about a beauty shot of the car?


:)

[rlmccarty2000]

I’ve seen a lot of this on reprints of this age and for whatever reason especially red. I could be many of the muscle cars of that era were repainted in red. Like others have said, not too much you can do about it except repaint if it really gets to you. From my experience though the paint does not fall off or anything of the sort.

I do wonder if Mike’s Meguires #7 approach might “moisturize” the paint to slow the aging process?

[timaishu]

I’ve seen a lot of this on reprints of this age and for whatever reason especially red. I could be many of the muscle cars of that era were repainted in red. Like others have said, not too much you can do about it except repaint if it really gets to you. From my experience though the paint does not fall off or anything of the sort.

I do wonder if Mike’s Meguires #7 approach might “moisturize” the paint to slow the aging process?

Having the paint fall off was my primary concern. It passes the 3ft distance without issue though!

As for whether its single stage or base clear, Im not sure. I have not polished/compounded it due to this reason. But I could see if I get any red rub off to know.

https://i.imgur.com/wwB4PbD.jpg
https://i.imgur.com/4SInKho.jpg
https://i.imgur.com/A825tY9.jpg
https://i.imgur.com/ubKCIsC.jpg
https://i.imgur.com/n24dRez.jpg
https://i.imgur.com/wIFynI6.jpg

[2black1s]

There's a lot of talk on this forum about how thin paint is. Many wonder why factory paint jobs are so thin. What you have here is a prime example of why.

I'd be willing to bet the farm that if you measured the paint thickness in those cracked areas you'd find it to be multiple times thicker than your typical new car.

While it's true that thicker paint films allow for more aggressive and repeated polishings, and most detailers see that as a good thing, excessive paint film thickness is not necessarily better than the thinner factory finishes. When exposed to real world environments, thicker paint applications are much more prone to cracking than their thinner factory counterparts. As an old painter, I think that is what you are experiencing... Cracking caused by excessive paint film thickness.

The only time I would ever see "extra" paint as a benefit is for a show car that will have only limited exposure to everyday environments.

As for your car, I think the only thing you can do to slow the progression of the damage you're seeing is to limit the future exposure to extreme conditions. The more you can minimize exposure to temperature extremes, especially cold, temperature swings, and excessive sunshine, the slower any further damage will occur.