Pimpled paint finish

[cococola]

I have got my 944 out this morning after 2 weeks of garage storage with a breathable cover on and upon close inspection to the paintwork on both sides have noticed that my paintwork is pimpled in certain areas.I did wonder if the cover on in damp conditions may be something to do with it or is it poor paint reaction? The guy I bought the car off did have paintwork tidied up about 12 months ago.Any ideas please?[]

 

[Diver944]

If by 'pimpled' you mean it has an orange peel effect then it is unlikely to have been caused by the cover, but is more likely that the paint shop did not spend a huge amount of time 'flatting and polishing' the lacquer once they had finished painting and baking it off.

If they have put enough lacquer on then it is a simple case of finding someone to flatten it out with very fine wet n dry (2000 grit or even finer) and then machine polish it back to a mirror like shine. The worry is if you don't know exactly which areas have been painted or where the new lacquer finishes, you run the risk of cutting back the edge of the fresh lacquer which will make it quite noticeable

 

[cococola]

Its not orange peely it is like an area of paint that you can actually feel the small pimples quite a few of them in one area and as though someone has painted over filings ,although this is unlikely because it has only shown up today.

 

[Guest]

ORIGINAL: cococola

Its not orange peely it is like an area of paint that you can actually feel the small pimples quite a few of them in one area and as though someone has painted over filings ,although this is unlikely because it has only shown up today.

If you have had paintwork done in the recent past it is possibly what they call Micro Blistering. This happens when low qualiity high solid/build primers are used and absorb moisture from either wet sanding or damp air. If this moisture is not dried in an oven or using infra red it stays in the primer and is sealed in by the top coat an lacquer until it warms up and causes expansion this is when the micro blisters appear. I remember having an arguement with a Berger Auto Finish rep in the 1980's when the had a poor batch of primer which resulted in me having to strip and repaint a 1967 Cadilac Fleetwod Limo.

Paul, what do you Chips Away guys use for primers?

Cheers
Tom

 

[Guest]

If your car is damp and you cover it, the damp is going to stay there. it's got nowhere to go. breathable covers really don't work, well they do in a heated garage but not in a cold damp garage. I'm afraid the moisture has getten into the paint and has caused the bubbling effect, two weeks with a wet towel wrapped around it, well that's going to destroy any paint.. If it hasn't gone too far you can flatten it. But if the primer starts coming through when you start rubbing back, it's bad news i'm afraid.

 

[cococola]

Does this mean that my car cover is a bad idea?[]

 

[colin129]

Car covers have been critisised before on here, maybe better for outside use as the air can still circulate, but then the cover can apparently rub the paintwork. If your car is in the garage, why would you need a cover anyway? Perhaps to keep the dust off? But you have paid a high price for the sake of half an hour with a bucket and sponge, which I would guess is about the time it would take to unpack and fit your cover, then remove and pack it away again.

Hindsight is a bit of a bu**er, I'm sorry to hear about your problems....

 

[Guest]

ORIGINAL: Darren

If your car is damp and you cover it, the damp is going to stay there. it's got nowhere to go. breathable covers really don't work, well they do in a heated garage but not in a cold damp garage. I'm afraid the moisture has getten into the paint and has caused the bubbling effect, two weeks with a wet towel wrapped around it, well that's going to destroy any paint.. If it hasn't gone too far you can flatten it. But if the primer starts coming through when you start rubbing back, it's bad news i'm afraid.

Moisture doesn't get into paint, paint is a sealant and non permeable. Even Nitro Cellulose of older years was non permeable. The moisture was in the primer or base coat from prep or not at all.

 

[sawood12]

I've always considered that covering cars for long periods of time is a bad idea. You can make the car as clean as you like prior to putting the cover on but wind will blow dust and sand under the cover and wind blowing the cover against the car will abrade against the paintwork. Also it is impossible, no matter how careful you are, not to get dust and sand particles on the clean side of the cover when removing and refitting it. If your car suffers condensation when uncovered it will only be worse with a cover - air circulation is absolutely imperative to help dry the car out - especially the interior of the car where the interitor fabrics can hold and retain moisture. How many times do you see car restoration programmes where someone finds a covered E-type in a barn somewhere, unpeels the cover only to find the rotting carcass of a car underneath?

Also as I understand it, although paint itself is impermeable, if the paint has not been applied to a perfectly prepared subsurface then it can be pourous, i.e. invisible minute 'holes' appear in the paint where the paint cannot adhere to dirty areas thus exposing the undercoat/metal underneath. This is why manufacturers warrant bodywork for perforation corrosion i.e. manufacturers defects. This could be what Cococola's car is suffering from due to a recent/previous touch-up or respray, though the use of the cover may well have sped things up a bit.

All might not be lost though. Depending upon the size of the areas might this not be a suitable candidante for S.M.A.R.T., therefore mininimising the extent of the repair? Maybe Paul Smith might be able to comment on what damage is S.M.A.R.T. repairable.

 

[cococola]

Thats a good shout Scott thankyou[]
Alan

 

[Guest]

ORIGINAL: sawood12


Also as I understand it, although paint itself is impermeable, if the paint has not been applied to a perfectly prepared subsurface then it can be pourous, i.e. invisible minute 'holes' appear in the paint where the paint cannot adhere to dirty areas thus exposing the undercoat/metal underneath. This is why manufacturers warrant bodywork for perforation corrosion i.e. manufacturers defects. This could be what Cococola's car is suffering from due to a recent/previous touch-up or respray, though the use of the cover may well have sped things up a bit.

Scott,

You are nearly right this can happen but usually leads to the lacquer going opaque and then peeling . This would not cause the microblistering that Alan mentions. On modern Cars paint is applied using a cathodic paint in process the the paint gun is charged with -negative charge and the bodywork is charged with a +positive charge. Very similar to and metal plating (gold/nickel/chrome etc) This way a uniform paint finish of a measured number of microns is applied. It is very rare for any oily impurity to attach to the bodywork before painting as the bodywork goes through degreasing bath before paint. I doubt that this is the cause here as impurity pin holes are quite visble
If the area is very localised and not on the bonnet or roof I am sure a S.M.A.R.T repair is possible. If the area is all over the panel well unfortunately it is a bodyshop job for strip back to metal
then acid etch priming.
Alan if you have a digi camera and can take a pic I am sure I can help you confirm if it is the dreaded micro blister

Cheers
Tom

 

[cococola]

Tom
I will post some pics tomorrow
Thank you
Alan

 

[Diver944]

ORIGINAL: tommo951
Paul, what do you Chips Away guys use for primers?

If I need to use a primer then I mix up my own in situ.

ORIGINAL:sawood12 Maybe Paul might be able to comment on what damage is S.M.A.R.T repairable.

It all depends on the colour, the area and what shape the affected panel is, our technique is best suited to a scuffed, gouged or dented bumper.From Cococola's description I don't think it would be an area a smart repairer could paint. If entire panels have pimpled in some way then it really sounds like a bodyshop repair is needed

 

[cococola]

This is a real weird one,now Iam really confused as today I was going to take some photos and one side has nearly cleared up and the other side is still pimply but not as bad as before.This is with me using the car the last 3 days and not using the car cover![8|][8|]

 

[Guest]

ORIGINAL: cococola

This is a real weird one,now Iam really confused as today I was going to take some photos and one side has nearly cleared up and the other side is still pimply but not as bad as before.This is with me using the car the last 3 days and not using the car cover![8|][8|]

It is definately the old microblister my friend!
You will probably find that once summer comes it becomes worse again. It is purely cosmetic at the moment and as our cars are galvanised I would not worry about it until summer. Then get it done or it will annoy you every time you polish!!

Cheers
Tom

 

[cococola]

Thanks Tom
I was hoping that it was dissapearing altogether!But at least I have an idea what to expect[]
Cheers
Alan