85 replies to this topic

[Dave W]

Can anyone tell me what the likely causes of paint bubbling are? Can it be avoided on a car kept outdoors in all weathers?

[LazyDonkey]

I've had mine for 7 years, it's never been garaged and last winter was the first time it's developed bubbles. Not sure it can be avoided, but using the car as often as possible clearing any snow off it is probably a good idea. IMHO covers etc don't make a difference, using the car does.

[rob999]

Rumour has it, it was due to the (lack of enough) baking of the clams when first produced... Prevention is as per LD says...even those kept indoors can get them although I think it lessens the risk.

[FLD]

Osmosis or water contained in the clamshell laminate and poor painting are the usual causes.

[fezzasus]

I'd be surprised if trapped water from the manufacturing process of the clams was still an issue. More likely at this age is damage to the paintwork allowing water to penetrate under the paint.

[FLD]

Water could penetrate from underneath, through any of the bolts into cavities etc. The only way to stop it would be if it were moulded in epoxy. For this reason I would always recomend an epoxy sealer as the first coat on a bare clam.

[Harry Hornet]

I'd be surprised if trapped water from the manufacturing process of the clams was still an issue. More likely at this age is damage to the paintwork allowing water to penetrate under the paint.

Car lives out all time

1. I had rear wing resprayed after only 6 months of ownership 9 years ago
2. 2 years ago after new clam and bonnet had to have complete respray on all replaced parts, looked like it had been to near a fire and had bubbles broken out all over, crap refurbish garage...."water/condensation" in paint was conclusion by independent investigation
3. Car has small bubbles here and there all over, I have learned to live with them but would never win a con course event unless there was a "smallpox" category

[slindborg]

From my research into osmosis and blistering on GRP products (think boats), my conclusions are: 1) Any 'emulsion' used in binding the glass prior to moulding that isnt fully soaked in resin CAN release water over time and then react with any uncured resin (there will be some) and create an acid which corrodes the surrounding areas. 2) Any moisture or acid trapped can/will freeze and thaw causing delamination/surface corruption. 3) sh** paint prep will never help. 4) 'only' cure is to grind out the corroded/blistered areas, steam clean, dry/bake, fill with a very very high quality polyester based filler or better yet epoxy, then epoxy sealer/gelcoat and finally paint. all imho of course.

[turbobob]

I would doubt it is osmosis. This has been discussed a few times. The paint and gel coat make it unlikely to be osmosis. It is more likely to have been absorbed into the GRP before gel coat & paint. GRP is a poros material so it will absorb moisture. There are the rumours that a number of the clams were stored outside before use.

[FLD]

I would doubt it is osmosis. This has been discussed a few times. The paint and gel coat make it unlikely to be osmosis. It is more likely to have been absorbed into the GRP before gel coat & paint. GRP is a poros material so it will absorb moisture. There are the rumours that a number of the clams were stored outside before use.

Gelcoat is still porous and absorbs water. See this spec sheet as an example
http://www.ecfibregl...aSheet/1483.pdf

[FLD]

From my research into osmosis and blistering on GRP products (think boats), my conclusions are:

1) Any 'emulsion' used in binding the glass prior to moulding that isnt fully soaked in resin CAN release water over time and then react with any uncured resin (there will be some) and create an acid which corrodes the surrounding areas.
2) Any moisture or acid trapped can/will freeze and thaw causing delamination/surface corruption.
3) sh** paint prep will never help.
4) 'only' cure is to grind out the corroded/blistered areas, steam clean, dry/bake, fill with a very very high quality polyester based filler or better yet epoxy, then epoxy sealer/gelcoat and finally paint.


all imho of course.

This almost how I would describe it. (Been looking into resin chemistry recently). Even the boat building resins (Lloyds approved) are susceptible to water damage.

[mbes2]

I know Joe-Turbo has a few new clams under warranty... they all still bubbled..... Mine has it around the boot area, but only along the join in the boot lip... (Tubby)

[turbobob]

I would doubt it is osmosis. This has been discussed a few times. The paint and gel coat make it unlikely to be osmosis. It is more likely to have been absorbed into the GRP before gel coat & paint. GRP is a poros material so it will absorb moisture. There are the rumours that a number of the clams were stored outside before use.

Gelcoat is still porous and absorbs water. See this spec sheet as an example
http://www.ecfibregl...aSheet/1483.pdf

So is paint to a certain extent. But they are both intended to repell water. Both the gel coat and paint / laquer combined should provide a pretty decent barrier to osmosis.

Edit at the end of the day if didn't repell water, it would be sh** useless on boats

Edited by turbobob, 21 December 2011 - 11:58 AM.

[slindborg]

I would doubt it is osmosis. This has been discussed a few times. The paint and gel coat make it unlikely to be osmosis. It is more likely to have been absorbed into the GRP before gel coat & paint. GRP is a poros material so it will absorb moisture. There are the rumours that a number of the clams were stored outside before use.

Gelcoat is still porous and absorbs water. See this spec sheet as an example
http://www.ecfibregl...aSheet/1483.pdf

So is paint to a certain extent. But they are both intended to repell water. Both the gel coat and paint / laquer combined should provide a pretty decent barrier to osmosis.

Edit at the end of the day if didn't repell water, it would be sh** useless on boats

Its not the repelling as such, its the fact there is water trapped in the GRP at the point of mrf/curing.

[ItsLikeAnElise]

Do the Lotus S2 clams have the same problem?

[techieboy]

Yes

[slindborg]

Do the Lotus S2 clams have the same problem?

apparently they do but not as badly, and it was mostly the earlyier ones (read VX era) that had the issues.

[turbobob]

I would doubt it is osmosis. This has been discussed a few times. The paint and gel coat make it unlikely to be osmosis. It is more likely to have been absorbed into the GRP before gel coat & paint. GRP is a poros material so it will absorb moisture. There are the rumours that a number of the clams were stored outside before use.

Gelcoat is still porous and absorbs water. See this spec sheet as an example
http://www.ecfibregl...aSheet/1483.pdf

So is paint to a certain extent. But they are both intended to repell water. Both the gel coat and paint / laquer combined should provide a pretty decent barrier to osmosis.

Edit at the end of the day if didn't repell water, it would be sh** useless on boats

Its not the repelling as such, its the fact there is water trapped in the GRP at the point of mrf/curing.

That's what I said in my previous post ...

Ideally the GRP would be dry, gel coat is then supposed to protect it and stop any moisture being absorbed.

[astravxr]

The VX was supposed to of been bad before i had it and it has had a respray on the back. Crap job IMO as it doesnt match the rest of the paint, its flat black and the rest is sapphire. Also you can see where the paint had been running on the back next to the exhaust... and theres dents in the paint if you get me, right next to the turbo spoiler. I pray to god i dont get bubbles or i'll cry, theres a few tiny bubbles on the front bumper which has been "touched" up before i had it

[turbobob]

Touching up will only mean it comes back I'm afraid. It needs treating properly to prevent recurrence.