Mystery bubbles under the finish!

Discussion in 'Other T-Types and Partscasters' started by TommyGunz, Jul 14, 2020.

  1. TommyGunz

    TommyGunz Tele-Meister

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    I just started to do the wet sanding on my new parts caster guitar, and decided to use mineral spirits for the first time as a lot of people said that won't cause a problem with wood swell which had cause the problem in the last guitar that I refinished. However, I now have these bubbles that look like pimples on the end grains and they are filled with mineral spirits. Has anybody ever had this happen to them? It looks like middle spirits may have gotten into some ingrained in the string holes and then traveled through the grain to the other end. What should I do? Given that the finish has separated from underneath, it looks like it's going to have to be stripped and then refinished. Thoughts?
     

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  2. rangercaster

    rangercaster Poster Extraordinaire

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    Sounds like inadequate prep work to me ...
     
  3. Intubator

    Intubator Tele-Holic

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    Yeah, that's called "solvent pop". Hopefully you can refinish that area if possible without affecting the rest of the body, as rangercaster said "prep work" and there are a lot of those boxes to check. It's 95% of the finish outcome of anything you refinish/paint.
     
  4. TommyGunz

    TommyGunz Tele-Meister

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    I was hoping with the criticism there would be some constructivism. I'm here to learn.
     
  5. TommyGunz

    TommyGunz Tele-Meister

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    The guitar was hanging to cure for 4 days after the last coat and it only appeared after I wet sanded for the first time using the mineral sprits. Isn't "solvent pop" the solvent used in spraying the lacquer like thinner? When I popped these bubbles it was definitely Mineral spirits and not lacquer thinner.
     
  6. sleazy pot pie

    sleazy pot pie Tele-Afflicted Silver Supporter

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    Have you said what the finish is?
    I don’t think that mineral spirits can go into the string holes and travel to the end and then create pockets.
    Look how uniform they are.
    They for sure weren’t there before you started?
    Did you leave the body in the sun by chance? I have seen something similar when I forgot about a body outside on a bright and hot day. But not exactly like that.
     
  7. sleazy pot pie

    sleazy pot pie Tele-Afflicted Silver Supporter

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    Oh, I forgot to mention- that top looks great. This is totally fixable. In the long run, it is a minor set back.
     
  8. TommyGunz

    TommyGunz Tele-Meister

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    The finish is vinyl sealer, then sanding sealer, then nitro. I didn't leave it out in the sun for sure. Somehow the mineral spirits got under the finish because I can pop them like zits and mineral spirits is definitely there. Really unexpected. I ended up just digging em out and removed all the finish layers above the vinyl sealer it looks like. I'll just have to start brushing lacquer into these areas until I get a similar build up. Real pain.

    Thx for the complement btw...I'm digging the finish too.
     
  9. hopdybob

    hopdybob Tele-Afflicted

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    now i always have problems with the translation because you have mineral spirit and white spirit but also turpentine.
    But this could be a reaction that that part wasn't completely clean of/dry of ???
    if that was water from wet sanding, ore , so i understand your writing but maybe wrong, wet sanding with mineral spirit.
    if your guitar was hanging with that part down, and the paint does not attach, fixate with the surface because there is something that will not allow it (like grease and water will not bond)
    the gravity will make you get those drops.

    but that is my opinion of what could have happened.
    this guitar looks like it is worth another effort
     
  10. stratisfied

    stratisfied Tele-Meister

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    That is a mystery. The mineral spirits would have had to migrate down the grain of the wood all the way from the string holes? You would have had to saturate the wood for that to happen. Also, vinyl sanding sealer and nitrocellulose lacquer are impervious to
    mineral spirits.

    A "solvent pop" occurs when the Lacquer surface dries too quickly relative to the underlying finish. The underlying finish continues to off-gas solvents and the solvent pools beneath the cured surface and dissolves the bond between the dried surface and underlying lacquer. The finish blisters and pops up.

    Did you sand the top first and then leave the rim to sand the following day or perhaps not notice the blisters as you wet sanded the top with the mineral spirits running off the top and down the sides and migrating into the blistered finish?

    Mineral spirits does not dissolve lacquer and could not have caused the blisters. It would have to be a solvent strong enough to dissolve the lacquer coming up from beneath the finish. Is it possible you applied a heavier lacquer coat at the end-pin where you overlapped your spraying and just didn't notice the blisters before wet-sanding?
     
    Last edited: Jul 16, 2020
  11. Rhomco

    Rhomco Friend of Leo's Ad Free Member

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    I have done this same thing way to many times over the years. The mineral spirits have found unsealed wood and penetrated. Let it dry a few days and go easy on the spirits. A few years ago the formulas changed dramatically due to VOC compliance issues. I now use charcoal lighter and seldom have the problem any more. Good luck with your project,
    Rob
     
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