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Thread: Tiny bubbles in paint, solvent pop? (Picture attached)

  1. #1
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    Default Tiny bubbles in paint, solvent pop? (SOLVED?! See page 3))



    Still getting tiny micro bubbles in the clear, even with just one coat. What am I doing wrong? Base had been cured for days. I've upped my air pressure 30psi, dropped down to a 1.3mm tip on a LVLP gun. (1.4mm tip on HVLP gun previously)

    This is cheap clear the shop recommended, ($120 gal low VOC, low solids, 4:1)... I'm wondering if it's not as easy to spray as it claims, or if I have other issues. Moisture? I've already changed my filter and still this. Considering trying out a new clear, perhaps SPI.
    Attached Images Attached Images
    Last edited by Komeuppance; 06-03-2019 at 06:30 PM. Reason: Updates on page 3

  2. #2
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    Yes, it's solvent pop. It could be the mix of materials or the temperature during application or the thickness of the application.
    Are you using a reducer made by the manufacturer of the paint? That can be a factor.

  3. #3
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    Quote Originally Posted by Len View Post
    Yes, it's solvent pop. It could be the mix of materials or the temperature during application or the thickness of the application.
    Are you using a reducer made by the manufacturer of the paint? That can be a factor.
    Thanks for confirming that. Paint shop guy didn't have any answers.

    I am not using reducer at all, just the recommended hardener for the temp range. I am spraying thin coats to ensure it doesn't go on too thick, but this still happens. Tech sheet doesn't recommend reducing it.

  4. #4
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    You mentioned your spraying thin coats so it doesn't go on too thick, but also said its one coat?

    If it's a few light coats back to back, its likely the same problem. too much too fast. If the top surface "skins" over before the solvents escape they will blow through. Usually happens quite a while after everything looks fine. If its happening right away, it could be some sort of contamination in the products, or air line? Sure looks like pop though.

  5. #5
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    Quote Originally Posted by Komeuppance View Post
    Thanks for confirming that. Paint shop guy didn't have any answers.

    I am not using reducer at all, just the recommended hardener for the temp range. I am spraying thin coats to ensure it doesn't go on too thick, but this still happens. Tech sheet doesn't recommend reducing it.
    A lot of low cost products will already have reducer in them. That's why they're less expensive. Allow your first medium coat to dry to the touch before applying a second coat.

  6. #6
    PainterDave Guest

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    that looks like fisheye or some other contaminate, IMO it is to random of spots, some bigger than others. and if it is happening as soon as you do your first coat is is exactly contamination.

    im sorry i just dont think that is solvent pop

    EDIT: i would lean towards moisture in the lines,

    what is your process all the way through ?

  7. #7
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    agree with dave. if it's happening on the first coat it's some sort of contamination. are you using a good hose? i feel for you, that dang fisheye can be a tough thing to figure out. does it go all the way through the base too?
    was the base still in the re coat window?
    look in the gutter in the upper right if the photo. see the small dots at the center of the crater? looks like fisheye there for sure.
    b marler

  8. #8
    PainterDave Guest

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    yeah those upper right ones are pretty big, look like the undercoat is showing in the middle of those as well.

    to the OP, grab a mirror clean it well and blow some air on it using a blow gun holding it real close for a few minutes. you will know if your air is wet

  9. #9
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    Default

    you mentioned base had cured for 4 days.... was it curing for 4 days prior to spraying the clear?

  10. #10
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    Thanks everyone for the replies.

    Quote Originally Posted by PainterDave View Post
    yeah those upper right ones are pretty big, look like the undercoat is showing in the middle of those as well.

    to the OP, grab a mirror clean it well and blow some air on it using a blow gun holding it real close for a few minutes. you will know if your air is wet
    I did this test. When spraying air, I can't see any moisture; however, as I release the trigger of the air gun, I can see a very faint hint of moisture. Is this the culprit? Humidity levels are at 52% right now, 66f and dry.

    I also did this test with my paint gun, but could not see the moisture at all. My air filter/water trap has been changed, and I still don't see it trapping anything at all. Maybe I need to upgrade my filter setup?

    The base was left to dry for two days, then scuffed and left to dry for a week. I've tried to eliminate as solvent pop variables as much as I could... waiting up to 30 minutes between coats, testing for tack on the masking, trying a slower reducer. Perhaps it's been moisture all along.

  11. #11
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    Default Filter...

    Quote Originally Posted by Komeuppance View Post
    Thanks everyone for the replies.



    I did this test. When spraying air, I can't see any moisture; however, as I release the trigger of the air gun, I can see a very faint hint of moisture. Is this the culprit? Humidity levels are at 52% right now, 66f and dry.

    I also did this test with my paint gun, but could not see the moisture at all. My air filter/water trap has been changed, and I still don't see it trapping anything at all. Maybe I need to upgrade my filter setup?

    The base was left to dry for two days, then scuffed and left to dry for a week. I've tried to eliminate as solvent pop variables as much as I could... waiting up to 30 minutes between coats, testing for tack on the masking, trying a slower reducer. Perhaps it's been moisture all along.
    I never use any gun of mine without a bubble/bulb filter right at the gun specifically to trap moisture. One is in the LINK below:

    http://autobodystore.net/Merchant2/m...Category_Code=

    Henry

  12. #12
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    Quote Originally Posted by Henry View Post
    I never use any gun of mine without a bubble/bulb filter right at the gun specifically to trap moisture. One is in the LINK below:

    http://autobodystore.net/Merchant2/m...Category_Code=

    Henry
    Thanks. Right after I posted I ordered a desiccant dryer filter (with replaceable elements), should be here by the end of the week.

  13. #13
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    You can cause those same solvent pop craters by reducing the pressure on your gun. You get a good looking clear coat application but the craters will show up in time. Try adding 10 PSI over your normal setting and see if that helps. Adjust your gun travel speed by watching the wet line develop where the fan is hitting the panel. Move the gun as fast as you can but still have the wet line develop. If you dwell while the wet line forms you will get runs or solvent pop from to much clear going down.

    Bob K

  14. #14
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    Quote Originally Posted by Komeuppance View Post
    Thanks everyone for the replies.



    I did this test. When spraying air, I can't see any moisture; however, as I release the trigger of the air gun, I can see a very faint hint of moisture. Is this the culprit? Humidity levels are at 52% right now, 66f and dry.

    I also did this test with my paint gun, but could not see the moisture at all. My air filter/water trap has been changed, and I still don't see it trapping anything at all. Maybe I need to upgrade my filter setup?

    The base was left to dry for two days, then scuffed and left to dry for a week. I've tried to eliminate as solvent pop variables as much as I could... waiting up to 30 minutes between coats, testing for tack on the masking, trying a slower reducer. Perhaps it's been moisture all along.
    seven days after scuffing the base is when you shot the clear? is that accepted practice for that base?
    b marler

  15. #15
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    Default Air compressor

    Quote Originally Posted by Komeuppance View Post
    Thanks everyone for the replies.



    I did this test. When spraying air, I can't see any moisture; however, as I release the trigger of the air gun, I can see a very faint hint of moisture. Is this the culprit? Humidity levels are at 52% right now, 66f and dry.

    I also did this test with my paint gun, but could not see the moisture at all. My air filter/water trap has been changed, and I still don't see it trapping anything at all. Maybe I need to upgrade my filter setup?

    The base was left to dry for two days, then scuffed and left to dry for a week. I've tried to eliminate as solvent pop variables as much as I could... waiting up to 30 minutes between coats, testing for tack on the masking, trying a slower reducer. Perhaps it's been moisture all along.
    When was the last time you drained moisture/water from your compressor tank. This really looks like a problem I had years ago and quickly narrowed it down to tank and line moisture. Also, if your compressor is getting on in years you could have a little oil blow by getting into the system and mixing with water in the tank if your not draining the tank regularly. Since that issue I got into the habit, decades ago, of draining my shop compressor every morning when I open up the shop even though I run a cooling compressor for my system. If you find this to be the culprit I would absolutely change my hose as well. Something to consider.

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