Bubbles in paint.

[tomfc]

Ok well iv brought some now paint for one of my projects and after painting the paint has come up with bubbles all over the panels, i first painted my bonnet and got this problem, so i cleaned the gun up and tried again with a new lot of paint on the door and it did exactly the same, so just to test i tried some old paint i had through the same airline and gun and that came out perfect...

So i tried the paint again and the bubbles came back...

Before anyone says, its definitely not dust, i double and tripple checked the panels after this happened on the first panel.

The paint is a sold 2pack, iv done alot of painting through the same supplier and never had any issues, i phoned them up to check i can just use normal hardener and 2pack thinners and they said yes so i guess thats not the problem...

Here are some pictures of the bubbles im talking about, theres literally millions all over the paint.

Anyone got any ideas?

 

[malcolm]

There are an awful lot of bubbles there. I feel your pain.

Couple of possibilities. In this weather is solvent popping could be possible (I think it's called that) where the outer surface of the paint dries before all the solvent has come out, and it pops up like that. Painting in sunlight would do it, otherwise a fast thinner in hot weather might be the problem.

Otherwise water in the air line maybe. Not sure how your system is set up, but you will get water bubbles in paint if spraying directly from the compressor. You would need a remote filter/regulator at least. Though water bubbles tend to pop up only after the car is bolted back together.

Try popping a bubble to figure out what's inside.

 

[malcolm]

Bit more info on Solvent Popping from a book (the excellent Vehicle Painter's Notes by Peter Child)

Popping is usually the result of air bubbles trapped during the application of the paint being unable to escape....

Causes:
hot and dry conditions
air pressure too low
Insufficient flash off between coats
excessively thick film
cheap thinner or incorrect thinner

It suggests doing the opposite of the causes, and also suggests a retardant in the thinners to lengthen drying time. That might be the same as not using fast thinners. Rectification flat off and try again.

 

[paintpot]

your SECOND COAT HAS DRYED OF BEFORE your first coat ,not allowing the first coat to evaporate.You need a slower thinner ,you are probably got a fast hardener and thinner.

 

[tomfc]

Thanks for the replies, im pretty sure this isnt related to the temperature as i painted the other day when it was alot colder and get the same results, i also tried some of the other 2k today when i painted this and that flowed out as normal...

I guess this might need a slow thinners, but the bubbles are there after its first coat, so i dont believe it to be a problem with the second coat drying before the first...

Its just a bit odd, how a different 2k paint by the same manufacture mixed with the same harden and thinners gives completely different results. Im 99% sure its a problem with the paint itself, be it its supposed to be mixed with something else im unsure, but it appears to go be normal apart from the bubbles, i did try on a panel i did last week and the bubbles are just lightly in the surface as they flatted out very easily with 1200...

 

[the snooper]

looks like water contamination to me.
how far away from the compressor is your water filter ?

 

[tomfc]

Surely that is illuminated as the bubble were not in the other 2k paint i painted under the exact same conditions?

Iv got a water catch mounted on the compressor and another water catch/pressure regulator mounted on the wall...

 

[the snooper]

ive known water filters to stop working when mounted too close to the compressor.
they tend to work by condensing the water from the tank so the longer the compressor runs the warmer the filter gets if eventually it gets as warm as the air passing through it, it will stop condensing.

so did you run the compressor for a longer period that day before painting ?

 

[tomfc]

No i hadnt used the compressor for about a week before, and its drained at the end of every day its used. Im pretty sure its not a water problem as surely this would have been apparent in the other paint.

 

[the snooper]

so you can rule rue water out then
the only other time ive had that sort of thing was a bad batch of paint which looked exactly like water in the airline
i sprayed a small part without a water filter and got similar results so flatted it off used a water filter and exactly the same threw out the paint got new and no more trouble

 

[bigtaloola]

It might be silicon in the air.
Have you got any cleaning stuff in the garage WD40 or stuff like that. If you have used that sort of thing it will stay in the air and settle on any surface.
just a thought
Dave

 

[Chipper]

It really seems to point to the paint itself, if other paint went OK in identical conditions the only difference is the material.
Is the paint and hardener from the same manufacturer?

As a test I suppose you could mix up the problem paint without thinners and brush an area on a clean piece of steel or similar, and do the same with the OK paint. pref the same hardener with each. That way there's nothing to react with (no primer) so if the paint bubbles it can only be down to the paint.