I’m looking for technical help or recommendations on: __paint chipping
Despite being kept outdoors in a very wet climate, the paint on my car has held up remarkably well. However, I’ve noticed over the last year or so that the edges of the section which lifts to allow the top to retract (not sure what the section is called) have started to chip.
It’s happening on both the front and back edges of the section and the white undercoat is showing in most of these chips.
Before I speak to anyone about getting the paint touched up I would like to understand the cause of the problem. Any ideas?
Thanks for the response. It’s not the bubbling - which I had on the bonnet, and which required a respray. This is a much more distinct series of chips along the edges. It looks like they have been banged against a hard surface repeatedly.
When I retract the roof the panel doesn’t seem to scrape as it settles back into position, nor when it lifts. Moreover, I’ve hardly had the top down over the last year because of a combination of bad weather and being out of the country for large parts of the summer.
Just checked mine carefully under strong light and no chips. One edge has no contact and the other rests on a rubber strip so this is a bit perplexing. Some pics would be a good starting point.
The bubbling on the bonnet is a different issue; ie: aluminum corrosion. I have that; irritating but a much slower process than steel’s equivalent.
On closer inspection it’s actually more like the paint has flaked off rather than chipped. What I don’t realise until reading this forum was that the deck lid isn’t actually made of metal. On the plus side, the flaked off areas won’t rust but I’m still a bit puzzled as to the cause. Do you think these bits could be touched up, or need a respray?
I had this on my NC2 and it was present when I bought it. I put it down to a reaction of the paint with the composite panel, possibly caused by expansion and contraction with temperature changes throughout the year. Coupled with the fact it’s the leading edge of the panel - particularly when the hood is down.
It didn’t get any worse in my ownership and I did discuss it with a bodyshop. It would have needed a respray to sort, and careful prep of the panel would be required to try and avoid it happening again. But they couldn’t/wouldn’t rule out it coming back again in time.
EDIT: this was mine, similar number/locations of the ‘dots’ on both sides. I used a Mazda touch-up paint with a small artist’s brush and that improved the overall look:
I think those “chips” were bubbles and the paint has come off. IanC provided a link earlier in this thread. You could just touch them Up but I think it would be noticeable.
“ What I don’t realise until reading this forum was that the deck lid isn’t actually made of metal”
The roof is not steel either, it’s resin.
Just to puzzle you a bit more, whilst the PRHT has a steel boot lid, the soft top has an aluminium boot lid and they are different sizes!
That is damage caused by either frost expanding trapped moisture (ice), or hot sun doing the same thing (steam).
Fibreglass boats, and cars, and filler repairs can suffer also, depending on the mix used at various stages of a build.
One of the problems with this kind of composite plastic is that it is hygroscopic.
Therefore it MUST be autoclaved for long enough to totally dry it before sealing with a NON-water-based undercoat before painting.
I found this out to my cost a couple of decades ago on a “flexi-rigid” circuit board where the flexi part was hygroscopic.
If anyone hastily soldered it, having forgotten to cook the board in an oven overnight at 85C, they could destroy internal connections (vias) when steam expanded the board. In the bin went £350 just for a board, and don’t forget to add £250 for maybe a hundred bits on it!
This was a very early CAD mock-up to see if everything would fit in the box…
Thanks for all this information, which is very interesting. I’ve had the car just over 6 years now, and feel it’s too late in my ownership to go to the expense of a respray. I’ll try and do a careful job of touching up the area - it might not look great, but it already looks very wrong, so…
Yep, take your time with the touch-up paint and it’ll be better than leaving as-is.
I’d recommend the genuine Mazda stuff, it seems to get the best match, plus a few small artist’s brushes rather than the included one which ends up applying the paint too thickly in my experience.
I’m sure the responses are the most likely causes, but an off the wall alternative could be crows trying to get at the seals and/or salt deposits on them. One place I worked we had a spate of damage to wiper blades which was found to be caused by crows.
For what it’s worth, I saw several examples of this issue on varying NC2 PRHTs when I was buying mine.
Different colours, different overall vehicle condition, stored inside/outside by the current owner. And in different parts of the country as well.
So I was fairly confident it was a paint reaction issue and just ‘one of those things’ that happened on PRHTs, probably more age-related than anything else. Likely due to more cycles of freeze/thaw as explained further up.
