Filler bubbling

Buford T Justice

Hi

My van seems to be suffering from a case of filler bubbling. Hopefully you can see from the photo's what I'm on about.

All rust has been taken away and it was filled and sanded a few times to get a smooth(ish) finish. It was then sprayed black a few times after three coats of primer.

Anyway, its started to bubble again under the pain. I know for a fact that its not rust, as when I was clearing some of the old bubbles it was just filler that had bubbled. I'm a bit confused as it hasn't cracked the filler. I know I read something about it before, but I can't remember what it was, or where i read it.

Can anyone shed some light on what's causing this please, and the possible remedies?

Thanks

andyseadog

i thought that was caused by moisture under the paint, or being prepped/ sprayed in a damp environment or something along those lines?

Buford T Justice

andyseadog wrote: »

i thought that was caused by moisture under the paint, or being prepped/ sprayed in a damp environment or something along those lines?

Prep and painting was done in the scorching weather we had a few weeks ago, so its not that.

Slidey

Did you wipe it down with panel wipe or Pre clean before you painted it?

Seperate

Fingers McGee wrote: »

Prep and painting was done in the scorching weather we had a few weeks ago, so its not that.

That's not really ideal either. You don't want to be working in extreme temperatures on either side.

Buford T Justice

Seperate wrote: »

That's not really ideal either. You don't want to be working in extreme temperatures on either side.

Fair enough, but the nice weather we were having would hardly be what you would call extreme is it?

Slidey wrote: »

Did you wipe it down with panel wipe or Pre clean before you painted it?

No.
Now that you mention it, I feel a bit of D'oh coming on. However, its not the paint that seems to be lifting, its a bubble in the filler. To elaborate a little, if I sand it down now, All I will get is filler until its smooth. There won't be any rust lurking behind. Think I'm doing something wrong here....

It was 'perfect' for want of a better phrase when it was painted less than a month ago. I just don't get it......

Buford T Justice

<Threads merged>

kev250

Where is the paintdoctor when ya need him;)

kdevitt

You should still have a moisture trapper on the gun, even if its warm out - they're needed here in the heat in Oz. Don't think thats the issue though.

That looks like the filler settled down though - being porous it could have absorbed water which then made its way out. Moisture in the paint would have left lots of smaller dimples I reckon.

Did you use a guide coat or spray putty over the filler?

vectra

100% certain that is the rust breaking out again..grind it off..Cut out the bad spots...treat metal with some chemical rust killer...Fill with Fiberglass filler...sand it down to shape..Fill with filler and sand until nice and smooth..Repeat your painting process.

Buford T Justice

vectra wrote: »

100% certain that is the rust breaking out again..grind it off..Cut out the bad spots...treat metal with some chemical rust killer...Fill with Fiberglass filler...sand it down to shape..Fill with filler and sand until nice and smooth..Repeat your painting process.

Doubt it. When I grind it off, its only filler that comes out and not rust., there's no rust behind those spots. May need to resort to that though. I know I read somewhere that if you (insert missing sentence here) the filler will bubble, but for the life of me I can't remember.

kdevitt wrote: »

You should still have a moisture trapper on the gun, even if its warm out - they're needed here in the heat in Oz. Don't think thats the issue though.

That looks like the filler settled down though - being porous it could have absorbed water which then made its way out. Moisture in the paint would have left lots of smaller dimples I reckon.

Did you use a guide coat or spray putty over the filler?

It was a spray can job. It was just a patch up until the bottom of the van gets painted again.