Bubbles coming up weeks after painting

J

Joshbot007

Promoted Users
Here is the background: my truck I am restoring and doing a color change on to bring up to standard. Stripped to metal using rotary sander, solvent borne wgr followed by waterborne, 2 wet coats spi epoxy, body filler (however on this problem panel no filler was applied as it was new), another 1:1 epoxy coat, epoxy seal coat, motobase base coat, 3 wet euro clear coats. Compressor setup is a 60gal with 55ft copper pipe to dry, filter, desiccant dryer, and disposable filter at the inlet of the gun (changed out after every 3 coats). Each coat was applied to the whole truck at once

Whats happened: been 2.5 weeks since spraying and I am noticing bubbles coming up on the passenger fender which was brand new. I also did find one very small bubble on the back of the cab but I'm ignoring that for now as it could be a dust nib, it’s very small while the passenger fender has a ton of them with a few big ones. Sun has been non existent here in PA since the day I sprayed it and had to move it out into the overcast and rain 4 days after spraying.

Any idea on what’s going on? Only thing I can think of is the new fender had an edip coating on it that I took off (probably 99% some trace amounts may have remained), wondering if they do an acid treatment before edip and that’s causing my problems?

Also any suggestions on how to stop it, or prevent it from getting worse such as deflating the bubbles and using a pin and putting touch up clear on or something? Leaving it as is and hope they stop growing? Its a work truck so just want to make the job last not as concerned about looks at this point just want to stop it where its at and prevent it from getting worse and causing major delam. Could potentially respray in the spring but not an option until then due to time and my “booth” getting too cold. Today is the first day of partial sunlight and I moved the truck to face that panel towards the sun to try to help it start drive solvents out hoping that will help. At this point just getting scared the rest of the truck is soon to follow and anything I can do (if anything at all) to prevent it I want to do asap.
 

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Most likely it's solvent trapped in the undercoats. That is the cause 90+% of the time when bubbling occurs shortly after painting. Take a sharp razor blade, slice one and smell it. Need to do it with 5 seconds or so of cutting it. If you smell solvent then you know that's the cause. If no solvent smell then it's probably water. More than likely one or the other.

Not knowing the times between coats, how long you waited between base and clear it's hard to tell you what you did wrong. I'll wait for others to comment on what to do. Only thing I know to try is to let it sit in the sun for as long as possible. Otherwise re-do.
 
thanks,

I can certainly let it sit for a few weeks to see if that helps at all and keep an eye on it. If there is any chance they settle back down on their own with time and sun id rather wait then start cutting them open and doing small clear touchups

I waited about 50min to an hr after the second fairly heavy coat of base until the first coat of clear. I was told about 30 minutes was what was required but my base coats were fairly heavy. It was a pretty hot day as well and temps in my “booth” were around 90 when I moved from base to clear. Slow reducer for was used for everything.

The strangest thing to me is still why it’s contained to this single panel (with the one small exception I may have found on the rear of the cab) while this panel was painted at the same time and on the truck as I overlapped the door right behind it and hood on top and not seeing anything on those as of yet
 
Looking at those bubbles from a common sense viewpoint, even if the bubbles deflat from sun exposer, what guarantee is there those deflated bubbles will adhere to the underlining substrate?⁸

The problem is isolated to that panel only. I'm leaning towards the E-coat that was removed with possible mirco particles that didn't get removed during final prep cleaning....

..... or, you didn't wash the e-coating with Dawn dish soap before sanding it off, embedded micro particles into the metal.

Whatever the reason, it sucks that it happened but, me personally, I would redo that fender.
 
Im thinking they would never fully deflate and bonding back I believe is not possible but not what im really looking for at this point, it is a work truck and if they can honestly just even stay what they are at right now without getting worse ill stay with until it bothers me enough to respray if that be in the spring or whenever. My biggest concern is getting worse and causing delam especially if it starts in other places and if there is anything I can do to prevent it. Sounding like sun bathing and seeing what happens is probably all I can do.

I did not wash the panel or any panel before or after stripping. The only cleaning done was after stripping sb wag remover followed by wb wag remover and epoxy
 
To further add, even though it's going to hurt emotionally, I'd take the advice given and slice one of those bubbles to see if you smell solvent.

That will narrow down the probably cause.
 
Sure, going off my best memory here are my coat times. Additionally, metal temperatures were kept at 75-95 deg f after all coats of anything for 24hrs. Metal temperatures after first two 1:1 epoxy coats did reach 120+ in areas close to the ir heaters but made sure to back them away when I did the paint day to not overbake

-Sb wag remover
45mins
-wb wag remover
1hr
- second 1:1 epoxy
40mins
-1:1 epoxy
3 days until started filler, 6 days since application until third 1:1 epoxy coat
-sb wag remover
45mins
- the third 1:1 epoxy coat
Overnight approximately 13hours
-sb wag remover
45mins
-reduced epoxy seal coat 25%
2.5 hrs
-basecoat
35-40mins
-2nd basecoat
I originally said 50mins but thinking back I believe it was actually 1.5 hours
-4:1:1 euro
20-30 mins
-2nd 4:1:1 euro
30 mins
-3rd 4:1:1 euro

I did lay on everything fairly heavy and the base coat did have a somewhat wet/clear look to it in areas but didn’t seem to change with time. Could be I put stuff on too thick and didn’t wait enough but the fender actually faired pretty well here wirh my heavier areas being on the doors and extended cab area
 
'68 Coronet R/T said:
This is the reverse of what I would recommend.
Once you cut a bubble open and smell it as Chris suggested, if it's not solvent you smell, then I would suspect that not all of the waterborne W&G remover was removed.
Click to expand...
I actually read to do that somewhere on this forum. I saw a few posts recommending to do it in that order but can certainly see that not helping
 
dhutton01 said:
You should supply the timing of all of your coats if you want folks to help you.

I saw something similar on FB and insufficient time after spraying epoxy trapped the epoxy solvents which then started migrating to the surface.
Click to expand...
Judging from the times given it is likely what Don said above here. Spraying unreduced epoxy and then coming back 13 hours later and sealing (then base and clear that day) is very likely the cause. Just not enough time. Why did you spray a coat of unreduced epoxy at that time? 13 hours, it would hardly have time to dry enough to sand. Did you sand it? Or did you simply spray it, wait 13 hours then come back and seal? Either way that is highly likely the cause. Not chastising you trying to understand so we can help you from making the same mistakes down the road.
 
If it is epoxy solvents, and it sounds like it is, then you are likely not going to smell solvents if you cut one open. The lack of any filler to absorb and more slowly release the solvents may be why it’s mostly on this panel. But that is pure backyard hack navel gazing… :)

Don
 
Well id say filler is only on about 10% of the whole truck with no panel having filler covering it 100% and there a few others with no filler. It was a color change work truck type project and my first time ever painting or doing body work so rage gold was all that was used when needed for welding areas and small dents, no skim coats or high build so if there was no damage visible to me then no filler got applied.

24hours after spraying 75-90 metal temp via heaters. After that it has been between like 75-55 air temp here day and night since I sprayed but overcast and rainy daily until today
 
2.5 hours from 25% reduced epoxy to base is also rushing it a little imo. Normally I would reduce 50% when spraying base that soon. However there are some widely varying opinions on this. I think it will depend on how heavily you sprayed the sealer.

Don
 
It was a wet coat. I was kinda just flying by the tech sheets, didn’t give much thought into waiting longer due to mix ratio
 
The problem IMO was the epoxy coat then epoxy sealer the next day (13 hours?) then base and clear after that in the same day. That's what seems the most likely. What sticks out the most to me. Basecoat sprayed too wet with not enough flash can do that as well, but it more often shows up as dieback in the clear.
 
Is there anything I can do to help drive the solvents out without creating more or larger bubbles in other areas? I assume sunlight but what about ir lamps overnight on different areas? Trying to prevent it his from starting to pop up on other panels
 
Joshbot007 said:
I think I saw that before but it was in reference to the strainers int he cup and not a disposable filter for the air inlet?
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Yes, pull the strainers in the cup as well, always.
But you are talking about something like this, right?

gun filter.JPG


If so, @Barry said they are totally useless and just restrict airflow.
Sound like you already have good air filtering and moisture control in place anyway.
 
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