PRHT paint & clear coat wrecked - now fixed (Picture heavy)

I have had my 07 NC1 Galaxy Grey PRHT for 3 years and when I bought it, I knew I would eventually have to get the hardtop, deck panel and door mirror cowling repainted. This doesn’t seem to be uncommon and affects those plastic/composite parts.

It was cosmetic to start with but then the rain started to get under the clearcoat. Well, it got so bad with the clearcoat breaking down and the misty colour worsening that now seemed to be the right time.

Got it back this morning from my friend’s paintshop and I’m very happy with the results. It’s a very good match with the otherwise great paintwork.

Let’s see how long it lasts.

The photos aren’t great but gives you an idea.

Before:

After:

John

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how did they do your rear deck I have had mine done twice (second time was free after it failed the first time) and it still bubbles
i eventually got most of my money back for the work
I would just be interested to know how they did it

We’d researched the forums, mostly on miata.net as it seems to affect more 5’s in the USA weather conditions, and moisture was the best guess for the cause. Interestingly, it was only a few colours that reported the issue, Galaxy Grey, Black and Stormy Blue were the most common. Also mostly NC1s but I guess that’s just age?

The composite panels were almost completely prep’d and then heat was applied for a couple of days to try to reduce residual moisture before getting to the final stages.

Only time will tell if it’s cured it or slowed down the return but I’ve repeatedly read of it coming back. Thankfully, I got mates’ rates so not a huge investment.

b0builder, did you get the milkiness on the main part of the panels too?

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no milkiness at all the panel looked superb when done then six months later there arrived back.
That is what we tried the second time i hope you have more luck than i had

This is the crucial bit! Job done properly.

Trapped moisture has a detrimental effect when frozen, because it expands. If the surface treatment is not fully watertight humidity slowly, slowly gets inside. Successive frosts build the bubble.

In very, very hot conditions it can turn to steam and again expand, destructively, as I found out twenty years ago with some expensive flexi-rigid circuit boards. The flexi bit is hygroscopic (like these panels on the car) and needs to be gently baked at 80C for at lest half a day before any re-work soldering can be attempted.
This pic shows a CAD mock-up to test the fit of what we were making. The yellow bit between the green boards is the flexi and carries circuit tracks, but where the vias (holes for plated-through connections) between the layers were expanded by steam from soldering nearby, it wrote off the board by breaking the connections.

I’m interested to see that other cars have paint bubbles on the deck panel. Mine is a Metropolitan Grey NC 3.5 with a small area of bubbling. As the deck is composite I was wondering how it had happened (it was there when I bought the car). I’ve been quoted £150+V to respray the deck. If it could reappear I’ll save my money.

mine went exactly the same as the photos.we had it sprayed and looked great for a year but the bubbles are slowly creeping back.wouldnt paint it again but maybe get it wrapped.