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Cracks around holes on freshly polished lacquer - Cause/fix?

Discussion in 'Finely Finished' started by chillman, Jul 26, 2020.

  1. chillman

    chillman Tele-Afflicted

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    Hi folks. Here's what I'm dealing with on a freshly wetsanded headstock:

    [​IMG]

    [​IMG]

    My guesses are either I sanded too thin and it wouldn't hold together anymore (I did sand through in a couple places that would be mostly covered by the tuner bushings, as you can see), or I sanded before it was fully cured. Or both.

    It's SW's Lovoc lacquer after 10 days curing time in climate controlled room.

    Anyone have this happen to them, or know for sure what causes it?

    And can I fix it, short of refinishing the headstock? I thought brushing on some lacquer might melt and fill it, and then I could level and polish again.
     
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  2. jhundt

    jhundt Doctor of Teleocity

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    the wet-sanding allowed moisture to get into the wood beneath the finish. The moisture in the wood caused the new finish to lose adhesion, and thus come loose during the sanding procedure.

    You have to do something to ensure that the sides of the tuner holes are impervious to water. A simple option is to rub them all around with whatever finish you are using, with a Q-tip. Or you can treat the holes with some other water-blocking material before you do the finish.

    At this point, your best option is to DRY sand the damaged areas with very fine paper, and re-do the finish.

    I am a big fan of wet-sanding; but when using the technique on wood surfaces, you must always be aware of the possibility for solvent (water) to enter the wood at un-coated areas.
     
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  3. schmee

    schmee Doctor of Teleocity Silver Supporter

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    Yep, what Jhundt said.
    If it's real cellulose lacquer you can melt it with Cellusolve solvent. Putting a coat of lacquer on it may do it too. Although it often dries too fast.
    i find you can brush on lacquer on a flat headstock like that with good results and a fine hair artist brush.
     
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  4. chillman

    chillman Tele-Afflicted

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    That makes sense, thank you for the thoughtful reply.

    Do you guys think I could brush on some lacquer as schmee said and then maybe spray on a couple of melty coats of 50/50 laquer/reducer to even it out some before flattening again?
     
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  5. T-Bone

    T-Bone Tele-Afflicted

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    Oh. Post is about a guitar headstock...
    I just saw “cracks around holes”.
    Never mind.
     
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  6. Freeman Keller

    Freeman Keller Friend of Leo's

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    Did you use a sealer? The only time that happened to me is when I didn't use a vinyl seal coat on maple before I shot the lacquer. I was able to melt some new finish in but I've always been afraid that I didn't have good adhesion to the wood.

    I would worry if your polishing compound had anything that might cause the subsequent coats to not adhere - silicon or wax or anything.
     
  7. Peegoo

    Peegoo Poster Extraordinaire

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    I wet-sand lacquer with low-odor mineral spirits. It won't swell the wood and it has no effect on lacquer.

    Another option is to press beeswax into screw holes and tuner holes before you wet-sand.

    Yet another option is to use a small artist's brush or Q-tip to coat the insides of the tuner holes with shellac or even CA before you apply your color/clear coats.
     
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  8. jhundt

    jhundt Doctor of Teleocity

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    I wish I could help you with this, but I don't know enough about lacquer. The one thing I learned about lacquer in all my years is - stay away from it! Way more trouble than it is worth, in my world.
     
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  9. schmee

    schmee Doctor of Teleocity Silver Supporter

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    It cant hurt to try just one of those spots at this point. As I said though often lacquer wont stay wet long enough. It appears to me though that those areas are "gone" enough you may as well sand a bit and put a coat of lacquer on the headstock.
     
  10. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    I agree.

    I would also add to not hang it when you spray it but leave it flat. It looks like the water ran downhill into the lacquer. I have limited experience, but many pros advise spraying the lacquer on a horizontal surface to keep it from sagging or running. Very thin coats are another good idea, and Dan Erlenwine suggests heating up the lacquer before you spray - at least with a rattle can.

    How to repair it? May be best to start over on the face ONLY by removing the lacquer and respraying that alone (flat), then blend in with the previous surrounding finish when you have roughly matched the same thickness. Then a few more light blending coats, then start wet sanding. May even want to paint the inside of the tuner holes with lacquer before starting to wet sand. Consider putting cotton balls in the holes after wet sanding to pull out as much water as possible before spraying the next few coats.

    You may be getting into trouble when wet sanding by not using a block or by sanding too deeply near the holes. You may be sanding through to the wood, which will suck up the water. I usually use a block in that area and just remove a touch of lacquer.
     
    Last edited: Jul 26, 2020
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  11. chillman

    chillman Tele-Afflicted

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    Yes there is Mohawk instrument sealer underneath. It looks like all the finish came up though, including the sealer. I only use silicon free compounds and I didn't get into any polish or wax before the cracks showed up so I'm pretty sure I'll be okay to clearcoat back over it. Worst case scenario is I refinish the headstock, I guess.

    Mostly though, is a body I finished at the same time with the same methods that I would very much like to prevent this from happening to, which is why I appreciate this advice:

     
  12. Blue Bill

    Blue Bill Poster Extraordinaire Ad Free Member

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    You can use naptha to wet sand as well; I like it better than MS. I agree, it looks like the water from the wet sand got into the wood underneath the lacquer and broke the adhesion. As you mentioned, getting wax anywhere near a spray finish is usually a very bad idea. I would skip the beeswax.

    Also, where's the decal?:D Keep the pics coming.

    When things go awry, sanding back and re-doing it is a normal thing; at least for me.
     
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  13. Boreas

    Boreas Tele-Afflicted Silver Supporter

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  14. chillman

    chillman Tele-Afflicted

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    I still don't know what to call the thing! It is my first build of an original design so I'll be sure to post updates.
     
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  15. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Blistercaster...
     
  16. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    Wet sanding isn't a process to be used on every project - it's a repair procedure for uneven lacquer, orange peel and other defects. If all coats are applied properly you should be able to go directly to buffing a few hours after the last clear coat is applied (assuming conventional lacquer use and not lacquer/enamel types like Deft and Colortone.

    This type of cracking, delamination and peeling is caused by water pr other liquid absorption during wet sanding and expansion of the wood.

    You many be able to flow it together using anti-blush spray, which is fogged at a 90 degree angle to the surface and allowed to "drift" down to the surface. If you spray it like lacquer it will run like mad!

    If may take several applications, and you WILL have to sand it level Seal the tuner holes with sanding sealer or wax to avoid repeating the problem - and it's be good to try to duplicate the problem on some scrap first so you'll know what to expect.
     
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  17. chillman

    chillman Tele-Afflicted

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    Thank you, I might try that before any more drastic option.
     
  18. Wally

    Wally Telefied Ad Free Member

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    Lacquer melt would be my choice to prep The situation for final coats of nitro. You can do a search for Frank Ford lacquer melt technique or somehting like that.
     
  19. Blue Bill

    Blue Bill Poster Extraordinaire Ad Free Member

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    Chillcaster!
     
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  20. chillman

    chillman Tele-Afflicted

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    Do you mean no sanding at all? Or specifically no wet sanding? Because even my best work has never been flat enough to take straight to buffing. I don't have a buffing arbor yet anyway, so the best I can do is my random orbital polisher. Is there a compound I can use with that to flatten orange peel? The orange peel on this latest finish is minimal but there will always be some.
     
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