Paint fail -- Glasurit Slate Gray

[techweenie]

Had an unhappy development on a 67S that was restored to original Slate Gray.

Beginning 6 months after the paint job, dark spots began to appear in the paint. Some are hard to see without sunlight or bright direct light and some are very distinct. There's no apparent pattern to where these spots are appearing.

Color sanding proved this isn't a surface discoloration, but is within the paint. We are going to strip and repaint the car, but in years of working with Glasurit, we have not seen this failure and we are looking for ideas. A paint expert told us an incorrect mix balance of filler can cause this, but the pattern and location of the dark spots are not related to filler (which was used sparingly and for the most part sanded to near-transparency). Further, the delay of 6+ months in appearance of these spots have us puzzled.

[mepstein]

I’ve seen something similar. It was on a hood that was a replacement on a 914. It had the spots but not the rest of the car. We never knew for sure what caused it but speculated that the hood had some chemical residue that eventually reacted with the paint and made the spots.

[Bill Douglas]

I'm thinking the same.

It's as if there has been an etch primer underneath and chemicals (acids) coming through. Or even an ordinary primer causing problems because the top coats didn't like the primer. Wrong/incompatible brand.

[techweenie]

Originally Posted by Bill Douglas

I'm thinking the same.

It's as if there has been an etch primer underneath and chemicals (acids) coming through. Or even an ordinary primer causing problems because the top coats didn't like the primer. Wrong/incompatible brand.

Glasurit primer and glasurit top coat, so not seeing incompatibility as a viable diagnosis. further, these spots appeared 7-10 months after painting, so not sure how "active" the paint was at that stage. That's why we asked for a sand and buff on the B-pillar to confirm it wasn't surface-only.

[962porsche]

not knowing just what the process that was done it's hard to say just what is going on.
I have seen this from people using pre body work cleaners instead of using pre paint cleaners.
a pre body work cleaner will take up to 30 minutes to evaporate off a panel when a pre paint cleaner will only take 3 to 5 minute. a painter may think it's ok to wipe down the car with pre body work cleaner then immediately tack off the car and start to spray. the solvents are still on the panel/s and now trapped under the sealer or paint. just takes time for it to show up.

I have also seen this type of thing from a painter that didn't use sealer . they have enough primer on the car so they block it and not having any break throughs from sanding to bare metal they spray over the primer. then months or a year later you start to see a ghosts of where they broke through just the layers of primer .


again it's all just speculating because I wasn't there as the car was being prepped and painted.

[82 sportsc]

962Porsche
Please elaborate on the sealer …
Particularly where there is primer & bare metal
Thanks
Frank

[82 sportsc]

962Porsche
Please elaborate on the sealer …
Particularly where there is primer & bare metal
Thanks
Frank

[962porsche]

you sprat primer and coats to build up layers this = mil build of the primer.
say you have 5 mils of primer you do your sanding but in areas after you may only be left with say .2 mils or even a small break through. the painter has no way of knowing what the mils are left in every area.
looks ok so they spray the car.
months or years later you start seeing a ghost of the thinner areas.
this can be even more prevalent when a car is premed then it's blocks then primed again AKA double primed. you can sand through the 2nd priming and to the 1st.

this can all happen when a car is sprayed with a epoxy or etch primer to replace the galvanized coat or to add more metal protection.
then the car gets sprayed with a high build primer.
the car gets sanded for painting and it gets sanded through the build primer and down to or very close to the epoxy or etch primer.
it may look ok at 1st for the 1st few months or year but as the paint cures and tightens up you see a ghost of the break through areas.

primers are made up of talc ( you know like talcum powered ) this makes them porous .
it's also what gives them a high mil build. the down side is with being porous it also gives your top coats more to shrink and soak into. the higher build the more talc.

this is why I'm a firm believer in always using a sealer over my primers.
NOT a primer sealer but a straight sealer.
you will hear some saying it adds to orange peal this is faults ! if it does they are not using it properly or they used a primer type sealer.

[962porsche]

you sprat primer and coats to build up layers this = mil build of the primer.
say you have 5 mils of primer you do your sanding but in areas after you may only be left with say .2 mils or even a small break through. the painter has no way of knowing what the mils are left in every area.
looks ok so they spray the car.
months or years later you start seeing a ghost of the thinner areas.
this can be even more prevalent when a car is premed then it's blocks then primed again AKA double primed. you can sand through the 2nd priming and to the 1st.

this can all happen when a car is sprayed with a epoxy or etch primer to replace the galvanized coat or to add more metal protection.
then the car gets sprayed with a high build primer.
the car gets sanded for painting and it gets sanded through the build primer and down to or very close to the epoxy or etch primer.
it may look ok at 1st for the 1st few months or year but as the paint cures and tightens up you see a ghost of the break through areas.

primers are made up of talc ( you know like talcum powered ) this makes them porous .
it's also what gives them a high mil build. the down side is with being porous it also gives your top coats more to shrink and soak into. the higher build the more talc.

this is why I'm a firm believer in always using a sealer over my primers.
NOT a primer sealer but a straight sealer.
you will hear some saying it adds to orange peal this is faults ! if it does they are not using it properly or they used a primer type sealer.

[Ooffenhausen]

We had some similar issues with Dolphin Gray, which uses a bunch of odd toners that didn't get used often. It's been a bit since I mixed Slate but that also uses some rarely used toners if I remember correctly. We had some in depth conversations with our local BASF rep and It came down to the toners not being completely mixed despite being on the mixing rack. Certain compounds in the toner had settled to the bottom and needed to be completely shaken before mixing or else it ended up with odd blotching in areas. Just a thought from some previous experience with some of the earthier(ish) glasurit tones.