Acrylic lacquer--how thin is thin?

Discussion in 'Finely Finished' started by Jupiter, May 15, 2012.

  1. Jupiter

    Jupiter Telefied Silver Supporter

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    Getting ready to spray my first guitar body in acrylic lacquer (auto paint) from rattle cans. I've done some research and read the can (not easy, since it's in Japanese), and it seems that I should apply it in several thin coats. But what exactly is a thin coat? Should it be misty, so that you see texture, or should it be wet to the point that it's a smooth glossy surface? Or misty at first and heavier for later coats, like some people recommend for nitro?

    The body has nitro/vinyl sealer on it, sanded quite smooth (400# grit). I'm hoping to finish painting in one day.
     
  2. Beatbx

    Beatbx Tele-Meister

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    You'd like to see it wet enough to juuust start flowing together but not so wet that it builds up on itself and runs. Overlap your strokes about half. Do practice it some on scraps before hitting the guitar. Good luck!
     
  3. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    +1

    And +10 - practice, practice, practice. Even if you use up an entire can until you get the procedure right. It's worth the effort and cost.
     
  4. Jupiter

    Jupiter Telefied Silver Supporter

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    Thanks, guys. And yes, I've been practicing a bit with some nitro on a dummy body. After that, and 3 cans of vinyl sealer on the real body, I'm starting to get it down. ;) I just wanted to confirm whether or not the technique would be any different for the acrylic lacquer.

    I'm going try a kind of whiteburst. My plan is to spray a couple of light coats of clear, with about 10 minutes between coats, then 2-3 light coats of white, to the point that the grain is just barely visible, then do the burst part, then more clear. I think it'll take 3 coats of white to get it even....

    My greatest fear is a paint run. I think I'm more likely to go too dry. :neutral:
     
  5. Jupiter

    Jupiter Telefied Silver Supporter

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    And I was right about that. I went too dry, got lotsa orange peel, sanded aggressively, and went through the color coat. :(

    On the second try, I went for much wetter coats--and got one big run, but the rest of it looks great, and I think I can sand that flat without having to spray again.
     
  6. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    It sounds like you might be mistaking "passes" for "coats".

    Each coat should normally be 2-3 passes, a few minutes apart. Each pass covers the entire surface with about a 50% overlap, but the first pass will not completely wet the surface - it's the second or third pass that gets the coating to flow together. At that point, a pebbly or noticeably wavy texture (orange peel) means you need to go a bit heavier each pass (or they are inconsistent); runs mean you laid it on too heavy.

    You can read label instructions, by the way, from pretty much any lacquer product that has them for general guidelines (except dry times, which may vary...especially with Deft). Any info about Duplo auto lacquer should apply fairly well to a Japanese product. With few exceptions, aerosol lacquers are very similar in application characteristics...but not necessarily in thickness, which is controlled by resin content and certain anti-sag additives.

    As far as "how thin is thin", you can get wet film thickness gages from industrial paint stores (shaped like a jagged metal credit card) for 5 bucks; sometimes for free if you're buying paint. When you test spray, you lightly press the side with the lowest numbers (starting with 1 mil, or one thousandth of an inch) into the wet film immediately - the film will touch one of the separated edges but not the next one - that tells you how thick you are applying the coating *wet*; then there's a calculation based on the solids-by-volume (the actual material that stays on the surface) percentage that will tell you how thick it will be when dry.

    Even professional painters rarely can tell what kind of coverage they are getting simply by feel. Almost invariably if they guess, they guess they are applying far more than the actual results. For amateurs guessing at thickness is literally impossible - might as well be throwing darts in the dark. Because lacquers are applied SO thinly (usually not more than 1-2 DRY mils...thousandths of an inch...per coat) I always test wet film thickness with a gage on scrap when using an unfamiliar product.

    The low film thickness and difficulty in maintaining consistency in application are primary reasons for applying multiple passes as a "coat" rather than trying to hit the mark in one pass. Only automated equipment used under tightly controlled conditions can pull off single passes - and even then some orange peel is usually present (look at the finish on a car - almost every one has a slightly wavy look to it).

    Typical wet film gage pictures and info (note - I do not work for Gardco. I do not think you can buy single gages from them anyway as they have, as I recall, an order minimum. This is for technical information only. They ARE handy and worth a few bucks.):

    http://www.gardco.com/pages/filmthickness/wf/callingcard.cfm
     
  7. Jack FFR1846

    Jack FFR1846 Tele-Afflicted

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    As you get on more coats, you can spray them thicker and wetter and they don't run as readily. Clear gets even easier and can be thicker than color without running.
     
  8. Jupiter

    Jupiter Telefied Silver Supporter

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    Thanks guys. I did much better the second time. I'm about done with my wet-sanding; gonna take my micro mesh pads to it and then wax.
     
  9. Jupiter

    Jupiter Telefied Silver Supporter

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    Doh! Towel marks!

    I guess the lacquer wasn't dry enough. :( I thought 1 week would be long enough for car paint, but apparently not.....

    Hope I can get the marks out before sanding through. :cry:

    How long should I wait?
     
  10. Thinlineggman

    Thinlineggman Tele-Afflicted

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    A month is generally enough time to make sure that it is fully cured, and sanding is safe.

    Make sure that you don't let any materials that react with laquer finishes come into contact with it. My bass that i used acrylic laquer on was put on display at 4-H fair (I used it as a project) and the table cloth that it sat on for a week left indents from the texture of the cloth and part of it was stuck to the thing. Really ticked me off that I didn't think to check!
     
  11. Silverface

    Silverface Poster Extraordinaire Ad Free Member

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    When I don't relic them I recommend 4 weeks before setting on stands, in cases or on cloth for more than a couple of hours, and 6-8 weeks before normal use.

    If I relic them I am sucking the plasticizers (the "flow" materials) out of them and in most cases a week or two and they're good to go for anything.
     
  12. Jupiter

    Jupiter Telefied Silver Supporter

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    Well, this is a real learning experience for me. I just assumed that since this paint was for painting cars, it would be really tough, non-reactive, fast drying, etc., but it turns out that it's not really that different from nitro. Does this mean I'm gonna have to worry about my strap, too?
     
  13. Thinlineggman

    Thinlineggman Tele-Afflicted

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    They're basically the same thing according to what I've been told haha. they even work with each other! I used a nitro clear on an acrylic color coated body.

    Every strap that I've used has been fine with lacquer finishes. It just scratches easier than poly would. Expect to have an old looking and feeling guitar in a couple years!!!
     
  14. alscort93

    alscort93 Tele-Meister

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    Dry time is also affected by the humidity, it was probably 2 months before my "VH1 Strat" was ready for sanding and polishing, and I used Duplicolor Perfect Match and a can of Truck and Van Clear.
     
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