Osmosis?

[mudhut]

Looks like I'm going to have to repaint the car sooner than I wanted to. :(

I'm pretty sure I have osmosis that is causing blistering on the paint surface. There are a good many (maybe up to fifty) fluid-filled bubbles, mostly on the on the tub and doors plus some on the headlamp pods. They vary in size from a couple of mm to about 10mm in diameter and the liquid has a distinctive smell - most closely resembling vinegar but not quite the same.

I've punctured them all to prevent pressure from causing the paint to lift further. My son recommends putting the car in a car oven for a while to see what else emerges so the defects can be dealt with.

Anybody able to confirm my diagnosis or had a similar problem?

[catswhiskers]

Can't comment on the smell as such Peter but I've also been told that before preparing fibreglass panels for paint, they should ideally be put on a 'low bake' cycle in a spray booth or similar for several hours. This tends to allow the trapped pockets of air to release from within the structure.

Mick

[chris.richard]

Definititely osmosis - the vinegary smell confirms it. Very unusual in non-immersed situation though.

[chris.richard]

some more info here (http://www.hempel.com/Internet/inecorporatec.nsf/vHEMPELDOC/60EAFE5C0398B51BC1256DE20055DE40?OpenDocument&1)

[mudhut]

Thanks Mick and Chris. That article is very helpful.

Looking like osmosis but it would appear not to be in the gelcoat but between the gelcoat and the paint. Can't deal with the problem completely until after I've moved and that could still be a year away.

[Shaun II]

Why has this happened to your bodywork and no one else, question of time, type of paints, type of storage? Bit of a pain, hope it can be stabilised and it's not a sand back to gel coat job.

[mudhut]

Good question Shaun. I think it has been how the car has been kept this year. UIt certainly wasn't like this when I bought it.

In the summers and having no garage, it has been under a so-called waterproof cover when raining and although I get the cover off to dry the car out, there have been times when it might have been under a damp cover for several days continuously.

In the winters it has been a) in a dry garage first year, b) in a dry garage with open front second year and c) under a motorsport awning with sides this last winter. Condensation has been a serious problem under the awning but the car hasn't exactly stayed soaking wet all the time.

I don't doubt that the cause is the way I've stored it though. Paint looks like two-pack.

[chris.richard]

But that's still a lot less moisture exposure than a boat hull.

[Chris J]

Paint looks like two-pack.

Yes it is two pack Peter.

Sorry to hear about this, by the way.