Howdi. Looking for some help today with SWMBO's classic mini. The poor little thing isn't entirely watertight so in bad weather we pull a waterproof cover over it. This has been extremely useful over the wet winter, but now we're getting heavy rain on much hotter days it's started to cause some damage to the paint on the roof. It's worth noting that the paint is already pretty bad having been sprayed at home by previous owner. A respray is on the books but we would like to avoid it for a while if possible.

Marks like these have appeared in the paint:

Polishing by hand with SRP made ZERO difference - the marks are definitely under the paint.

A bit of reading suggested that condensation was becoming trapped underneath our waterproof cover, which was acting a bit like a greenhouse, and being drawn into the paint due to the hot weather. At night the paint would cool and moisture is now trapped in the paint.

Several sources then suggested that if I could hear the paint up enough to let that moisture evaporate the marks would dissapear. Boiling water or a heat gun were suggested. As the milder option I went for boiling water:

Not the result I was hoping for. A lot of the bluish grey marks here have polished out by hand, but equally, a lot have been left behind and it looks fairly awful now.

At this point, I'd be fairly open to any suggestions for what's going on here and what I could try to sort the paint out. Respray ing is our last resort really, but I'm even a bit concerned that if there is moisture trapped in there, it might still come back through.

What do you think folks?

EDIT - pictures fixed.

Edited 14 June, 201411 yr by Maieth

Sorry...but this looks like a respray

If the paint has been damaged..it will have to be repainted

Not a surprise. Quality of the existing paint was awful and there's no evidence of any lacquer or clearcoat.

Was just hoping there might be some kind of way to clean it up. Ah well

If you are planning to have it professionally resprayed in the future, I would say you have 2 options, first rattle can the roof just to improve its looks until the respray, or second have the roof wrapped.

If there is moisture a wrap is no good, it will bubble up within weeks.

Sorry that is a professional boy shop referral, not much in detailing terms will make a difference as Chris has suggested.

From that little picture it looks like a grey fire effect decal, do it to the rest of the car.

That looks like the cover has a rough surface and in windy weather has abraded the cars bodywork

From that little picture it looks like a grey fire effect decal, do it to the rest of the car.

Haha. Yeah, I did think it looked quite cool. SWMBO less impressed.

Get it sorted now! If you have moisture under the paint then it's got in somewhere so oxygen can get in as well. Could rust without you seeing it until you get a sunshine roof that is!

Get it sorted now! If you have moisture under the paint then it's got in somewhere so oxygen can get in as well. Could rust without you seeing it until you get a sunshine roof that is!

 

The cover is no longer in use. As this was the only reason any moisture got under there in the first place (if it is indeed moisture) it is unlikely the problem will get worse unless it is used again. SWMBO is certainly happy to put up with soggy footwells and steamy windows for a while if it means stopping the roof getting worse.

We'll get a refurb/respray of the roof sorted when time and money allow and I may rattle can it in the garage in the meantime, if I get a free weekend.

 

As far as rattle can painting goes, what is the best way for me to get a bit of gloss back into the paint after spraying? I can borrow a DA polisher from a mate, but product advice on polishing it up would be appreciated.  I'll be effectively polishing a t*rd (the paintjob, not the car) here as a temporary fix, so I'd like to avoid the need for expensive gear.

Rattle cans obviously will not give as good a finish as a pro job but I have managed on older cars to get a half decent finish. Preparation is the key.

 

This assumes you are not looking for a concourse finish and the car is not so valuable as doing this will devalue it. I can't see from the photos (if it is an ex Paddy Hopkirk rally Cooper S then don't do it, you will immediately lose 20k!)

 

You need to get well above the roof to spray so you are looking down on it.

 

1) rub roof down with 1200 grade wet and dry, mask all surrounding areas.

2) spray roof with a primer/filler

3) rub roof down again

4) Top coat 1 - shake the can, have a beer, keep shaking the can, have another beer keep shaking the can thats a good ten minutes.

5) Top coat 2 - start spraying before the roof panel i.e. it would be like spraying the windscreen if you covered it up. This is to get a regular flow of paint going before getting into contact with the roof.

6) Use about 30cm away from the roof surface and spray with a continous stroke the full length of the roof, don't stop half way because when you start again you will have an uneven level of paint and overspray mist. After each run stop and shake the can again, don't be tempted to use the can until it runs out. It will start to spit lumps of paint which is a pain. As soon as its starting to sound empty get a new can.

7) Continue until the roof of fully painted. Don't be tempted to go back over any missed bits. Wait until it drys (give it an hour or so) and repeat the process a second time.

8) leave for 24 hours then ploish (by hand) with your favourite polish. I find Mer works great on freshly finished paint. It doesn't strip off the paint but does a good job of flattening the surface and giving a good shine. Not quite a showroom finish but not at all bad. I wouldn't use a power polisher on rattle can paint.

 

This is only my opinions and suggestions but I am sure there are many more on here who can give you some tips, maybe some kind hearted sole near you might have a mobile paint sprayer.

A great guide ....Nice one

Yes, I agree.

Its really special when someone takes the time and trouble to help in that way.

Rattle cans obviously will not give as good a finish as a pro job but I have managed on older cars to get a half decent finish. Preparation is the key.

 

This assumes you are not looking for a concourse finish and the car is not so valuable as doing this will devalue it. I can't see from the photos (if it is an ex Paddy Hopkirk rally Cooper S then don't do it, you will immediately lose 20k!)

 

You need to get well above the roof to spray so you are looking down on it.

 

1) rub roof down with 1200 grade wet and dry, mask all surrounding areas.

2) spray roof with a primer/filler

3) rub roof down again

4) Top coat 1 - shake the can, have a beer, keep shaking the can, have another beer keep shaking the can thats a good ten minutes.

5) Top coat 2 - start spraying before the roof panel i.e. it would be like spraying the windscreen if you covered it up. This is to get a regular flow of paint going before getting into contact with the roof.

6) Use about 30cm away from the roof surface and spray with a continous stroke the full length of the roof, don't stop half way because when you start again you will have an uneven level of paint and overspray mist. After each run stop and shake the can again, don't be tempted to use the can until it runs out. It will start to spit lumps of paint which is a pain. As soon as its starting to sound empty get a new can.

7) Continue until the roof of fully painted. Don't be tempted to go back over any missed bits. Wait until it drys (give it an hour or so) and repeat the process a second time.

8) leave for 24 hours then ploish (by hand) with your favourite polish. I find Mer works great on freshly finished paint. It doesn't strip off the paint but does a good job of flattening the surface and giving a good shine. Not quite a showroom finish but not at all bad. I wouldn't use a power polisher on rattle can paint.

 

This is only my opinions and suggestions but I am sure there are many more on here who can give you some tips, maybe some kind hearted sole near you might have a mobile paint sprayer.

 

That's fantastic.  Thank you very much for taking the time to put together such a detailed response. I reckon this is worth a go, was starting to feel it would be too much work.

As for the value of the car - not an issue. We bought it for 2k and have probably already added another £500-1000 just through some time and care.  As noted earlier, a proper re-spray is inline, but likely at least 6 months away while SWMBO gets saving and our friendly neighbourhood mini and classic specialist clears a backlog of work.  No way I'd be looking at a rattlecans for my own mini, for example.

 

Any thoughts on the quantity of paint needed?  The panel is roughly 2.5m2 (1.2m x 2m....  ish) and obviously I want it to have 1x nice even coat of primer and 2x topcoat.  How many cans am I likely to need per coat if I'm trying to price it up?

 

Thanks again for advice so far to everyone.

Edited 18 June, 201411 yr by Maieth

That's fantastic.  Thank you very much for taking the time to put together such a detailed response. I reckon this is worth a go, was starting to feel it would be too much work.

As for the value of the car - not an issue. We bought it for 2k and have probably already added another £500-1000 just through some time and care.  As noted earlier, a proper re-spray is inline, but likely at least 6 months away while SWMBO gets saving and our friendly neighbourhood mini and classic specialist clears a backlog of work.  No way I'd be looking at a rattlecans for my own mini, for example.

 

Any thoughts on the quantity of paint needed?  The panel is roughly 2.5m2 (1.2m x 2m....  ish) and obviously I want it to have 1x nice even coat of primer and 2x topcoat.  How many cans am I likely to need per coat if I'm trying to price it up?

 

Thanks again for advice so far to everyone.

I would reckon, looking at Halfords prices as a guide, the following: 2 filler primer 300ml, 8 top coat 300ml (four for each pass to be on the safe side) all come out at £6.49 = total £64.90 + the wet and dry and a bar of household soap (you know the big green bars from fairy - this picks up and holds the small particles when you do the rubbing down stage - wet the 'wet & dry' with warm water, rub the soap onto the 'wet & dry' then use, rinse frequently). Obviously it goes without saying that you don't need to rub down between top coats. As a guide to the speed of the runs over the roof, think you are stroking a cats back to keep it calm, thats roughly the speed of application and use one continuous pass for each run. Don't worry about a bit of misting, it should polish out. If not sparingly use some t-cut. Get the one made for metallic paint rather than the normal one for solid colours, it's gentler on new paint.

As a guide to the speed of the runs over the roof, think you are stroking a cats back to keep it calm, thats roughly the speed of application and use one continuous pass for each run.

 

 What an amazing analogy.  Again, thanks for the advice. Will talk to SWMBO, see if she trusts me to do this

No problem - good luck, I know my wife would not let me anywhere near her car, not even to drive it!

No problem - good luck, I know my wife would not let me anywhere near her car, not even to drive it!

 

  I wish.

She won't bother with a garage if she thinks there's a chance I can do it. I've done more rewiring than any man should need to, fitted a stereo and speakers from scratch, replaced the radiator, water pump, brake hoses, tie bar bushes and engine steady and done the head gasket twice (did it once, then decided we should have had the head refurbished so took it off again  ).  The joys of classic car ownership I guess.

It's going ok!

I started last weekend and got the roof washed down and wet sanded, then fully fried off.

First coat of primer went on ok but didn't cover very evenly and 2 cans was only just enough to cover so I put a second coat down.  I've wet sanded this back now and I'm very pleased with the finish so far. Such a satisfying process, taking the rough spray down to a smooth finish. The original paint is slightly visible in a couple of small places, but talking to a couple of body guys, as I'm using black on top it should still cover fine.

 

Hoping to do top coat number 1 this evening.  Fingers crossed.