microblistering - help!!!

[FMH]

right guys, i recently had my e46 m3 resprayed in house of kolor shimrin paint.
the car was primered last year and left in the drive, 3-4 months ago, i sent the car to be painted.
the guy rubbed the primer, sprayed the car in white (groundcoat) and the the shimrin on top.

now, after the winter has gone, i looked at the car which was outside, it has microblistering all over it. went back to the painter who says its cause the primer has absorbed water over the year it was outside.
googled, microblister and it says its possibly becuase of not enough drying time between base and top coats, or water/oil in the compressor or air line.

confused to hell, but whats the real reason and whats the best cure

thanks in advance

[Doblo]

The reasons why do not matter any more, you need to start afresh, leaving the car sat in primer for that amount of time was not a good idea.

[Kos]

did you have the car covered after the paint ?

[FMH]

did you have the car covered after the paint ?

just for 3 days as the roof was off, that was in nov. the cover was one of them 4m sheets that you use in a spray booth, not a proper cover.

[cecotto_singh]

Can be down to the existing paint on the car being too thick.
Most probably down to water on the primer.
Just happened to my mates Porsche.

[mattmk1]

water, silicone or grease on the panels/primer is normal cause. oil / water down the airlines creates a different effect. Can you get a photo up i should be able to tell if its a clear picture?

[beardymat]

you shouldnt leave cars standing around in primer for long periods of time as its porous and this will be compounded if it was outside. I would say this is your main problem but other factors as listed already can also cause it. its back to the drawing board im afraid, no other way.

[skipunda]

Sorry to hear it FMH

[FMH]

So thats £2.5k worth of paint and labour down the drain!

Thing is, the primer was flat down just before the spray job, so wouldn't that have got rid of moisture as it was indoors for 12 weeks getting prepped final time.

i feel its between the white base/shimrin/clear coat.

Oh well, going back in May when the weathers better, might just get away with a flat and spray as the blisters are tiny or not?

[beardymat]

I have had a similar problem with a job we did the year before last, We got the paint suppliers technical guy down to look at it and even he couldnt explain fully what caused it as the job had been fine for several months but when left outside in the snow it microblistered. The strange thing was that it settled back down afterwards although was still evident in places so we repainted it again. When we rubbed it down again you could see where the spots had been because the paint came away straight away in these areas as the adhesion to the primer had been broken. The problem also appeared on my dads car which had had a little work but again in the snow and again settled down but we left it and its been fine since, go figure.

We repainted the car free of charge by the way and the paint manufacturer agreed to supply materials as clearly paint shouldnt do this. However we were responsible for the job from the start.

[FMH]

Well, my painter has suggested that i leave it till summer and it may settle. Does that not mean it will come back again next time its cold/snowing.
Also, like you say the paint came away easily from the spots, if i was to flat and spray in summer, would i get blisters in between the blisters previously rubbed down?
Complicated sh*t, i know where i'm going tomorrow morning, try forking some paint out the supplier.

[e30topless]

it won't "settle" it hasn't adhered to the Panels,

[beardymat]

its hard to say really, i would prefer to see it all rubbed back like we did.

My dads car didnt flare up again even in this years snow but im sure if you went at it with the DA you would see the little spots of low adhesion appearing. It depends on who foots the bill as to what you do i would say.

[FMH]

If i can get a most likely answer to the question "will it rise more next time it snows or gets cold", i will get a rough idea of what i need to do.

Had a look and iirc, its only happened where the snow sat. Bootlid, Bonnet, top edges of wings, doors, quarters.

[Low_E30]

^^ Definently looks like it was weather related, as its where the snow, ice ,etc etc was left to sit on...

Had one of my Mercs painted by a very competant body shop early last year, got it back about the same time we had that snowfall last year....And same as you guys, it blistered up where the snow and rain sat on like the bootlid, bonnet, tops of wings, doors rear quarters....

The two wings were new from M-B, rear quarters bootlid had never seen paint & the bonnet may have had a blow in for stone chips at some point.... so the blame clearly lay with either the paint or the application of paint, as Matt says paint should never do this....

I personally suspect the really cold icy weather stops the new paint from adhesing correctly...
Needless to say, they repainted it for free, I then left the car in the garage for the next 6 months due to other commitments and the paint has been fine ever since...touch wood!

From what I remember we were able to move the blisters along under the paint with our finger nails... The paint also lacked lustre and shine where it had blistered...but had looked like a million bucks when I first picked it up....

[powelly]

Just chatting to the paint techy bloke here at work, he's of the opinion that the problem lies in the length of time left between primer and paint, the adhesion properties of the primer are seriously deminished if it's left too long, 14 months is one hell of a long time.

[B7]

Just chatting to the paint techy bloke here at work, he's of the opinion that the problem lies in the length of time left between primer and paint, the adhesion properties of the primer are seriously deminished if it's left too long, 14 months is one hell of a long time.

You beat me to it steve.

The primer will have completely cured. Add the the fact it's pourous and has absorbed moisture, there you have your problem.

Then its painted and a short period after it sits with inches of snow over it. Recipe for disaster .

[lee131]

you cant leave primer too long and never should it get wet as its pourous so it will let the moisture penetrate, ive had primer blister on cars when stored indoors but just damp so understandably if outside its going to suffer

[Z3I]

As well as the primer absorbing water over that long period, which is the most likely cause, the new paint may not have cured completely before it was allowed to get wet. On new car production the paint is cured by baking perfectly, and never allowed to get damp between any coats, thats why new car finish is so hardy. If the refinished paint is allowed to get damp at all between coats then it will certainly absorb water. Only the final coat, when baked to a glaze is virtually non-porous.
If any water has been absorbed, it will then be trapped, and will boil under the finished paint even in weak winter sun, causing the blisters.
They will not settle down at all, and the only solution is to remove all the new paint back to old finish at best, or base metal at worse, all of which will be more costly than the initial paint job.
If you only let a new paint job dry cure, and not bake, then theres a high risk of blistering in the first few months as the paint absorbs moisture.
Proving where the problem lies and who is at fault is virtually impossible

[powelly]

As well as the primer absorbing water over that long period, which is the most likely cause, the new paint may not have cured completely before it was allowed to get wet. On new car production the paint is cured by baking perfectly, and never allowed to get damp between any coats, thats why new car finish is so hardy. If the refinished paint is allowed to get damp at all between coats then it will certainly absorb water. Only the final coat, when baked to a glaze is virtually non-porous.
If any water has been absorbed, it will then be trapped, and will boil under the finished paint even in weak winter sun, causing the blisters.
They will not settle down at all, and the only solution is to remove all the new paint back to old finish at best, or base metal at worse, all of which will be more costly than the initial paint job.
If you only let a new paint job dry cure, and not bake, then theres a high risk of blistering in the first few months as the paint absorbs moisture.
Proving where the problem lies and who is at fault is virtually impossible

That's not strictly true, most of the process is down to the type of thinner/hardner used, intact if you so wish you could use an air dry thinner, no baking required, same durability different application technique, you can also get fast thinner, slow thinner, the list is huge. The paint used on production lines is a different beast altogether, this is thermosetting, it doesn't contain any hardner and is high baked at approx 180 degs, for just a few minutes.

[Z3I]

As well as the primer absorbing water over that long period, which is the most likely cause, the new paint may not have cured completely before it was allowed to get wet. On new car production the paint is cured by baking perfectly, and never allowed to get damp between any coats, thats why new car finish is so hardy. If the refinished paint is allowed to get damp at all between coats then it will certainly absorb water. Only the final coat, when baked to a glaze is virtually non-porous.
If any water has been absorbed, it will then be trapped, and will boil under the finished paint even in weak winter sun, causing the blisters.
They will not settle down at all, and the only solution is to remove all the new paint back to old finish at best, or base metal at worse, all of which will be more costly than the initial paint job.
If you only let a new paint job dry cure, and not bake, then theres a high risk of blistering in the first few months as the paint absorbs moisture.
Proving where the problem lies and who is at fault is virtually impossible

That's not strictly true, most of the process is down to the type of thinner/hardner used, intact if you so wish you could use an air dry thinner, no baking required, same durability different application technique, you can also get fast thinner, slow thinner, the list is huge. The paint used on production lines is a different beast altogether, this is thermosetting, it doesn't contain any hardner and is high baked at approx 180 degs, for just a few minutes.

Thats just how it was explained to me by a pro paint sprayer some years ago when I was spraying an MG TC that had the blistering before I painted it. I'm sure there technologies that can get round most problems at cost, but are not always applied if the sprayer wants a job quickly out the way. Most important, he said, was not to allow anything to get damp.