17 replies to this topic

[SolarB]

Sprayed my car earlier this year with 2k and it all looked good for some time. I cut and polished the thing after a week of letting it harden and it came out ok (well I was happy at least) but 6 weeks after spraying imperfections started to appear.

I've listed the process in some detail in the hope that some bright spark can tell me where I went wrong.

Took a year to fix the body shell and I used Halfords spray paints (etch, primer and gloss) to seal the panels while the repairs were finished.
2k high build primer applied once the repairs were finished and it immediately reacted with one of the many gloss cans I'd used, not a crinkle reaction but it pulled back in a crinkle pattern.
Sanded down the high build and applied a thin coat of Barcoat paint.
2k high build over the top of this. No reaction, sanded with 400 grade.
Several thin coats of 2k over the top and all looked well.
All paint applied in warm dry conditions with each application of primer on a separate day. The last application of primer had a week to dry before the top coat was applied. 5-6 thin colour coats all applied on the same day.

Six weeks after polishing I've had three different reactions starting to become apparent.

Very small pin holes started to appear on the front wings and rear panel. They look like miniature meteorite craters.
[attachment=87834:P1070758_b.JPG]

Pot marks on both A panels (rear edge of both). Flat bottomed.
[attachment=87835:P1070774_b.JPG]

Ripples appearing (very difficult to photograph). Looks like ripples left in the shallows on a sandy beach but on a very very small scale. At the moment these ripples are still developing and spreading after spraying in the last week of April.

Now the paint was near as damn it perfect when I'd finished the cutting and polishing and the imperfections were not there. The puzzling thing is the length of time they took to appear. Had they shown on the day of spraying or the following day I could understand the problem but a month and a half? To make it more interesting none of these problems have appeared where I had the first reactions with the Halfords paint.

I'm resigned to sanding the car back to metal and starting again but I'd like to know what went wrong. The atmosphere was dry, the air supply filtered and had a water trap. There were no silicones or other contaminates in the garage or on the car. The paint, activators, thinners and all additional materials came from a reputable supplier. The paint is fine on the doors, boot lid and bonnet but these were all treated in the same way, there is no difference in materials or the process.

Does anybody have an idea of what I did wrong?

And it was all beginning to look rather good.....
[attachment=87843:P1070776_c.JPG]

[GreaseMonkey]

I think the craters are caused by silicone, did you use panel wipe before spraying?

[SolarB]

I think the craters are caused by silicone, did you use panel wipe before spraying?

Yep, panel wipe. The A pannels and front end were the last items replaced so had the least ammount of time to pick up contamination. I'm the only one that uses the garage and there were no oils or silicones used anywhere near the car or even in the garage for the 2 months before the spray job. It's got me puzzled.

[kirk]

you sure the same marks wernt there when you primerd it
and may be missed to see them bad prep or solvent pop in the primer

and when you painted it fresh 2k paint theres a chance you couldnt see them before but now the paint as had time to shrink back there showing ?

normaly happens more with single pack tho not with 2k
only thing i can think of sorry

either that or its deffo silicone

Edited by kirk, 30 July 2009 - 09:18 PM.

[jack_marshall]

I've never seen silicone marks appear time after painting, they always appear pretty immediately while the paint is being put on.

Without seeing the car by eye I'd hazard a guess that it is all sinkage of some sort.

Its a shame as the finish looks fantastic.

[SolarB]

I've never seen silicone marks appear time after painting, they always appear pretty immediately while the paint is being put on.

That's what I've always believed. You can cut and polish 2k the next day, it's the huge delay that really bugs me.

Without seeing the car by eye I'd hazard a guess that it is all sinkage of some sort.

I'm leaning towards a problem with the primer under the pot marks as they are large (2-3mm across), though as to what it could be I don't know.
As for the pin holes I can't believe any primer problem would come through the top coat. It looks as if the wife has been out there with a needle and pricked it,...........................hold on a minute! (only kidding).

Its a shame as the finish looks fantastic.

Why thankyou but I can't take any credit for the finish, that's what a week of wielding a polisher loaded with G3 will do to any paint job.

[SolarB]

you sure the same marks wernt there when you primerd it and may be missed to see them bad prep or solvent pop in the primer

Definately not there, 100% sure of this. The polished surface was fine for a month or so before the marks appeared.

and when you painted it fresh 2k paint theres a chance you couldnt see them before but now the paint as had time to shrink back there showing ?

2k does shrink, seems to take about a week to completely stop shrinking which is why I waited a good few days before cutting. Again it's the long delay that I can't explain.

normaly happens more with single pack tho not with 2k

Yep, if it was celulose or a spirit based paint I wouldn't be so surprised.

either that or its deffo silicone

I'd bet a large sum of money it wasn't contamination in the garage or on the panel as I'm the only person who uses the garage.

Is there a chance that the paint was contaminated in the tin before I bought it?

[chunkytfg]

spray gunn set up?

Did you have a proper regulator with water and oil filter plus another oil filter by the gun?

i'd go with silicone myself though

[jack_marshall]

Silicone tend to form perfectly round and immediately during paint so I would say not so.

There's a problem with your prep somewhere.

In my experience and opinion these are the only materials that should be on the car, in this order.

Bare metal
Filler
Etch
Primer
Seam Sealer (Ive used it before primer with no problems either)
Topcoat

Using these in the right order with enough time between, you will get no reactions or strange movement under the topcoat.

Anything else like barcoat, stopper, putty is a no no. Pin holes and such should always be filled with the same filler used before primer as its less likely to sink than the above.

Edit.. I dont suppose the problem areas are areas of filler as you remember?

Edited by jack_marshall, 30 July 2009 - 10:58 PM.

[SolarB]

There's a problem with your prep somewhere.

In my experience and opinion these are the only materials that should be on the car, in this order.

Bare metal
Filler
Etch
Primer
Seam Sealer (Ive used it before primer with no problems either)
Topcoat

Using these in the right order with enough time between, you will get no reactions or strange movement under the topcoat.
Anything else like barcoat, stopper, putty is a no no. Pin holes and such should always be filled with the same filler used before primer as its less likely to sink than the above.

I applied a very thin coat of etch only on bare metal (though there was a slight overspray on existing paint and filler). No stopper, only filler (Isopon Metalik - fantastic stuff) and this was under the high build primer. I blow sanded filler with an air line and this exposes any voids that have filled with dust and the high build had a week to settle before sanding so I'm pretty certain that it's not filler problems.

The Barcoat was only applied to areas where I had a primer reaction and (so far) the top coat problems haven't coincided with the areas which have Barcoat underneath.

Edit.. I dont suppose the problem areas are areas of filler as you remember?

Pinholes have appeared on areas which have filler and areas which haven't.

Is it possible I've applied too much filler primer and something is happening underneath the top coat? The primer had a week of good weather to dry but I'm still leaning towards primer rather than top coat problems.

Managed to get a half decent shot of the ripples (though it's still not a particularly good photo).
[attachment=87873:P1080482_b.JPG]
This is the wing/scuttle area. It was perfectly smooth but you can see I now have a very pretty textured effect.

[roofless]

did you wet sand between the coats of High build? last roof I did got sinkage like that in the high build primer as we put on successive coats, luckily we spotted most of it and used regular filler and fine paper sanding to cure them, but we missed a few also and by the time top coat and laquer was one we got pretty much what we see here - it was immediately obvious though, not like it appeared over time

[SolarB]

spray gunn set up?
Did you have a proper regulator with water and oil filter plus another oil filter by the gun?

New filter and regulator on the tank, nothing on the gun end.
I bought a new air line for this job but I sprayed the doors, bonnet and boot first with the new line. I'm assuming any contamination in the air line would have shown up on these items and not the body shell.

[SolarB]

did you wet sand between the coats of High build? last roof I did got sinkage like that in the high build primer as we put on successive coats, luckily we spotted most of it and used regular filler and fine paper sanding to cure them, but we missed a few also and by the time top coat and laquer was one we got pretty much what we see here - it was immediately obvious though, not like it appeared over time

Now you're asking, spent so long on this thing. I might have wet sanded at some point on some of the primer but I can't remember. Weather was very hot for the week so I can't believe it's actual water. Can wet sanding give other problems? Cut primer that's turned into a paste and filled voids? (though how I get voids in a spray applied primer I'm not sure).

[minidaves]

well how about trying to flat and polish it again, as you are not happy with it, if you rub through then you are going to repaint anyway, and as for paint jobs all cars have inperfections if you look hard enough

dave

[SolarB]

well how about trying to flat and polish it again, as you are not happy with it, if you rub through then you are going to repaint anyway, and as for paint jobs all cars have inperfections if you look hard enough.

Yep, going to do that and see if it's settled down yet. My only fear is that I get the thing on the road and a year later the paint falls off.