New Paint on Project, Some Concerns

[DuhFool]

Hi All,

Great site, have looked around before, but now have some questions.

I am reassembling my project car, a 1968 Dart, pro touring, show car. The paint and body work was finished last summer, and I have been working on it when I can over the past year to get it back together.

The issue I am having is that I am noticing that the paint seems to be "brittle" and is cracking/flaking around fasteners. For instance, reassembling the door mechanics, there are bolts, etc. that hold the glass channels in place on the end of the door, the latch mechanism, etc. When I just start to touch the surface of the paint, it cracks on me. A few places it has actually "flaked" off and appears to be down to the metal. I am by no means cranking down on these fasteners!

Here were the steps used during the paint/body work. If you need specifics I would have to ask the guy that painted the car.

Products:

- Dupont Chromabase Etch
- Dupont Chromabase primer
- Dupont Chromabase sealer
- ProSpray base coat (high solids)
- ProSpray clear coat (high solids)

- Removed all paint with D/A sander
- Did metal work, etch primed and undercoated any "blind" spots before they went back together (i.e. inside of quarter panel, wheel houses, etc.)
- Exterior panels, same deal. Etch, prime within recoat window, block, re primed, etc.
- Sealer applied before base coat
- Base coat applied as directed
- Clear coat applied as directed

The other thing I am seeing is that the clear seems to be more brittle than I would have imagined it to be. Generally, with clears they seem more "rubbery" if that makes any sense. I would not have expected the paint to chip like it is, but maybe it is something with the underlying coat so the top coats cannot do much to hold it together.

I would appreciate any input, I know there is a lot of experience on this board. I am worried about driving the car, and getting the inevitable stone chips, not really knowing what is going to happen...

Thanks for all the help. :)

[Len]

Some paint products chip and crack more easily than others and the thicker the overall coating is from the metal to the top coat the easier it will chip or crack. Almost any paint will crack or chip when you tighten a bolt down on it. We usually do most bolting onto a painted surface prior to the paint application for this very reason.

[DuhFool]

I understand what you are saying, although reassembling this portion of the car before paint would be impossible. At least on this particular car. These are points of adjustment, so painting them in would be a bad idea in case they needed to change.

If this is fairly normal, I guess I will stop worrying about it. I would have expected it to be more durable than it is.

Thanks.

[Mark G]

This sounds odd to me. The etch primer should adhere really well and not flake tobare steel. How did you get your doors and other panels down to bare metal. Did you DA all the panels down to metal, or did you use stripper, sand blast? Then, did you do a phosphate wash or anything? Was anything soda blasted?

I've actually had this happen under two circumstances:

1) I soda blasted a bunch of parts, blew off, vacuumed clean (with a brush), but not washed the soda off with water. I painted the parts pretty much like you did. When I went to install the paint flaked off big time, like you are describing. I had to strip all the parts (used stripper this time), wash and re-paint. The paint was coming off in 1" or larger sheets.

2) Performed a phosphate wash on a steel panel and must not have thoroughly washed off the phosphate. I thought I did, but in any event, the paint did not adhere and flaked off like you are describing. This was early on in my paint and body days and frankly I don't know what I might have done wrong there, but it really created a lot of extra work for me. Soon afterwards they came out with self-etching primer and I didn't have to use it.

Mark G

[DuhFool]

Mark,

Parts were *not* soda blasted, nor was phosphate wash used. I know the panels were wiped down prior to painting, I can get the details on what exactly. I would assume prep solvent or something similar, but I cannot be sure.

Everything was taken down with a D/A sander. Panels were scuffed per Dupont reps instructions for good adhesion. I didn't want to blast because it is a phenomenal mess with material ending up everywhere. I know soda will dissolve with a wash down, but neither me or the guy that did the work were comfortable with the surface prep that comes after soda blasting.

The bare metal is what worries me too. I can see maybe breaking the paint down to the primer, but not to bare metal. I spent a lot of time and money on the project, and wanted to make sure we did it "the right way" in terms of protecting the metal, adhesion, etc. and when I see this happening it is somewhat disheartening.

Thanks for the reply.

[DuhFool]

Here are some shots so that you can see the scuff. If etch cannot adhear to this, I'm not sure what it would take...

65836584

[Len]

Another variable that can cause the paint not to adhere properly is IF the primer was applied too dry. If the wrong technique or fluid tip size were used and the primer went on dry it won't bond well with the surface.