[Spray Enamel] How much to sand color before clear?

Discussion in 'Tech-Talk' started by Yonatan, Sep 27, 2020.

  1. Yonatan

    Yonatan Squier Talker

    Age:
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    Jul 21, 2020
    Israel
    I'm getting ready to clear coat the spray enamel (RustOleum 2x), but I have a dilemma about how "defect free" the color coat should be.

    I wet sanded with P800, because 1. There was lots of orange peel 2. Seems that the usual recommendation is to sand the color to promote adhesion of the clear

    It's very flat now, but the problem is that looking closely I can see scratches/inconsistencies/etc.

    I'm concerned that if I sand with a finer grit, the clear won't stick (as it is there is already some "shine" from the P800), and if I sand with a courser grit, it may look even worse!

    I know that enamel doesn't blend in like lacquer, but will the clear somehow mask the scratches leftover from the sanding?

    This is a fairly light color (Ocean Mist), if that matters.
     
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  2. beagle

    beagle Squier-Nut

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    I wouldn't sand it at all if I could help it.
     
  3. nmagi

    nmagi Squier Talker

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    AFAIK you can go till 2000 grit wet/dry and be still on the "satin" velvet-like side, nothing fancy or shiny and non sticky, I cannot even imagine what kind of shine you say you get from #800 and I have buffed quite a lot of clear coats layers such way, and metals too **. But I have never dealt with the adhesion thing like yours -colour to coat- so I may be wrong but first of all it can be tricky so you should be careful. You will have to clean the surface too before coating

    **I now thought you might be talking about she kind of shine a clogged s/paper gives , you should have in mind that too. . Anyway I go with #600 then a 2000 grit most of the times
     
    Last edited: Sep 27, 2020
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  4. LAPlayer

    LAPlayer Squier-Meister

    232
    Jul 9, 2020
    LA / Denver
    For me it would be first prep the wood so that when the color is applied it is without scratches or defect. Second, I would rub it lightly with 0000 steel wool to knock off anything that might have stuck to the color. Then I would clear coat it - multiple coats.
     
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  5. dbrian66

    dbrian66 Dr. Squier

    Age:
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    Jul 14, 2017
    Maryland, USA
    I normally sand The primer with 400 before I paint the color coat. And then no sanding at all between color and clear. After the clear cures, I start with 600 and go all the way up to 3000.
     
  6. nmagi

    nmagi Squier Talker

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    The thing is that he has orange peel effect on his paint. Another thing is that many times people sand the paint to get over with some dry sprays or stuff like that but I guess that would be nothing more or less than a #2000 wet/dry sandpaper. I don't know how to get away with the paint 's orange peel, but one way could or could not be sanding. I would sand and paint again anyway
     
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  7. metalmerchant

    metalmerchant Squier-Meister

    352
    Mar 25, 2011
    cornwall UK
    Going finer with your paper is only tickling the scratches, if there isn't the depth of base colour to flatten with P600, then I would still do so, and dust on another coat of colour.
     
  8. Yonatan

    Yonatan Squier Talker

    Age:
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    Israel
    To clarify, the only scratches are the ones from wet sanding. The problem is that there was a lot of orange peel with the color coat. This was my "I can't remember how many"th attempt at the color coat and even with all of the tricks (heating can, shaking it constantly, overlapping strokes, etc.), I still get orange peel (o.k. I don't think I'm laying paint down heavily enough but then when I try to I get runs). So, hoping to avoid yet another color coat, I wet sanded down the orange peel, and it's left a good but not perfect result. There are some fine scratches and swirl marks from the wet sanding. Maybe I should wet sand again, with P1000 instead of P800 to see if it will smooth things out. Other option is to go to a courser grit (I have enough color on it), but I don't see how that will improve things.

    I somehow discovered that wet sanding in small circles almost leaves an acceptable result, but not quite, instead of long scratches I have subtle swirls. The question is how much will that show under the clear.
     
    Last edited: Sep 29, 2020
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  9. Uncle Joe

    Uncle Joe Squier-holic

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    I would think once you make the commitment to sanding the basecoat you would go finer to lose swirls, not coarser. I'm painting a Mustang now and I ended up with a couple of slight imperfections and a tiny run on the back of the horn. My plan is to spot sand to 2000 on Halloween and leave the front of the guitar without touching it prior to clearcoat.

    When I watch guys spraying cars with the paint I selected, they don't sand at all and they do primer, basecoat and gloss within 48 hours. Comes out nice. I'm trying to do better so I'm facing the same quandary, to sand basecoat or not to sand basecoat. That is the question. I'm certainly going to sand the clearcoat once I get there.
     
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  10. Yonatan

    Yonatan Squier Talker

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    I'll try that, the question is, at what point will the grit be too fine for the clear coat to have something to grip on to?
     
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  11. Uncle Joe

    Uncle Joe Squier-holic

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    I honestly don't know.
     
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  12. Yonatan

    Yonatan Squier Talker

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    Fair enough!
     
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  13. nmagi

    nmagi Squier Talker

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    I really think you should be more worried about your paint and coat compatibility, but there wont be any problem at all with #1000 if they re compatible
     
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  14. Jay Jackson

    Jay Jackson Squier-Nut

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    When I do enamel I make sure the temp is very warm like 80 to 90 this helps to keep orange peel away. I do light coats letting each coat to get tacky before the next coat and I do the same for the clear applying it over the tacky enamel.
     
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  15. Yonatan

    Yonatan Squier Talker

    Age:
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    Jul 21, 2020
    Israel
    I'm testing on scrap (over RustOleum color):

    1. RustOleum 2x clear. Took a couple of months to cure! I was initially concerned about the durability, but actually seems to be hardening up nicely. I can still scratch with a fingernail, but only if I really try to, but even then there isn't any separation of the clear coat from the color coat.

    2. Blonde shellac. Hardened up very nicely (despite usual claims that shellac isn't very durable). I can't scratch it no matter how hard I try. Obviously imparts a color. I got some bleached shellac powder though (which should be closer to transparent than the Blonde) if I decide to go this route.

    3. Wipe on poly (water based), still curing...seems fine so far, but I can't really compare yet.

    I can't get automotive stuff, so those are basically my options.
     
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  16. beagle

    beagle Squier-Nut

    907
    Nov 19, 2017
    Yorkshire
    I find that none of the hardware shop paints ever harden enough to be used on guitars.
     
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  17. Yonatan

    Yonatan Squier Talker

    Age:
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    Jul 21, 2020
    Israel
    Just to update, I wet sanded with P1000 and then P1200 and it brought the color coat to a much better place. Might be ready for clear coat, need to examine carefully. Just hope this fine grit sanding won't create any problem with adhesion of the clear coat.
     
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  18. metalmerchant

    metalmerchant Squier-Meister

    352
    Mar 25, 2011
    cornwall UK
    It is possible that the clear coat adhesion may be compromised through ultra fine sanding of the base coat. however the clear will disguise fine sanding swirls. Try to resist laying on too many coats of clear as it may suffer small crack lines (I'm not a junkie!) Later in time as the wood naturally expands and retracts. There is still the option of cutting and buffing the clear if you are not satisfied with the glossy finish rather than slapping loads on.
    Good luck and keep us all posted.
     
  19. Yonatan

    Yonatan Squier Talker

    Age:
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    Jul 21, 2020
    Israel
    Gonna set it aside for now (still haven't decided on which clear coat to use):

    wetsanded1.jpeg