- My model of MX-5 is: __2009 prht
- I’m based near: __
- I’m looking for technical help or recommendations on: __paint
When I bought my car back in January 2019, there were very obvious bubbles in the paint, on the bonnet. The rest of the car seemed in good condition, so I went ahead with the purchase.
In that time, if hasn’t got any worse - although sometimes the bubbles shrink and then later expand. The underside of the bonnet shows no sign of any problem.
The dealer suggested it was an issue with Mazda’s paint finish back in 2009, and neither my local garage nor the guy who did the undersealing (and seems to know the model) well had any real idea. Neither of them thought it was rust.
The bubbles are a fair size at maximum expansion. I’ve ignored it up until now, but it’s beginning to bug me. I’d like to be better informed before making a decision on what to do about it. Any suggestions from anyone that has had this issue, or seen it, would be very welcome.
I’ve added some pictures, but it’s been raining so there are raindrops in there as well. The bubble are the larger shapes. I’m tempted to burst one with a needle, but concerned that it will then look worse.
Thanks
The good news is it won’t be rust, the bonnet is aluminium. Normally, if that’s the correct word the leading edge of the bonnet gets hit with lacquer peel or bubbling of the paint as in your case. It’s the oxidisation of the metal, yep more likely poor prep.
Check around the boot lid numberplate lights, they can start bubbling the paint up. In your car the boot lid will be steel, ali on the soft top lids.
No real fix apart from grind back and touch up or have the whole panel painted, the bonnet.
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I have had a similar thing, it turned out to be Brake fluid that had dripped down from a car that was stored above it in a garage.
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Get it repainted…problem solved.
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Don’t burst it as it will crack and flake off. It looks like it’s delaminates paint. It either hasn’t been prepped properly before paint or it’s lifted to to corrosion of the aluminium. It’s a shame for a car of that age but not uncommon.
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Thanks all - I will resist the temptation to burst the skin of the paint blister! For the time being I will have to live with it, but a respray might be on the cards in the future. Main issue with that is that I’ve heard some horror stories about respray - with poor prep being a not un-common factor. I would also not want to undertake any remedial work myself - the combination of lack of space (no garage or driveway) and lack of patience doesn’t lend itself to that approach.
I’ll just have to avoid looking closely at the bonnet for a few months!
Moisture entrapment. We used to see this problem a lot when painting aluminium trains on a cold, damp day and the train had not been put in the paint booth for long enough to thoroughly warm up before painting. Only solution is to strip bonnet back to bare alumium, leave the bonnet in a heated paint booth to warm up and dry out the moisture and then repaint. Remember aluminium is porous so you need to be thorough in preparation to make sure it is warm and dry before painting.
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