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  1. #1

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    My son has an airbrush which he normally uses to spray his model planes and i'm going to finish a custom made pickguard made of curly maple with it. I have no experience at all with spraying and need to know if i can apply it directly onto the wood and how many layers of (clear) nitro lacquer i need to spray. Also what the approximate waiting/drying time would be in between applying the layers.
    Thanks!
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  3. #2

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    Well, until a professional chips in...I've done some nitro refinishing on a couple of guitars, using both spray and brush ( yes, you read that right,,brush). The short answer is that it will depend how absorbent your wood is, but usually 6-8 coats is enough. As you know, you sand nearly all of the nitro off, between coats and when finally wet sanding it, so most of the nitro goes to fill the grain anyway.

    I started using a brush after having read that Daniel Slaman sometimes brushes on the nitro in the earlier coats - it works fine, for clear and solid finishes .You could try brushing on 3 coats, then wet sanding it, and then putting on the final coats with the airbrush ( which does take some practice, it's not as easy as it seems). Stewmac microgrits are excellent for the final wet rubbing out.

    One thing I would not do is use an aerosol can, sometimes the nitro has far too much plasticiser in it, giving a sticky finish.

    That's what I do, but let's see what the pros say..I could be doing it all wrong

  4. #3

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    WEAR A GOOD QUALITY MASK and eye protection!

    How about just rubbing on Danish Tru Oil? French Polish is much safer and therapeutic to apply.

    Nitro can be rubbed on, I am sure. Brushing it on is a lot better than spraying when you don't have the proper mask.

  5. #4

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    ...or, there's the waterbased lacquer alternative, too. Not so easy to work with, but definitely safer. French polish is safe, but takes some skill to get that mirror finish.

    If you do use lacquer, outside - with no wind, if spraying- is best. You can brush it on even when windy

  6. #5

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    If you must use Nitro please be careful. You must consider the toxic nature of this outdated finish product. Regardless of how you apply nitro proper venting of the shop is a must. Nitro is time consuming. It has a slow curing time is and requires multiple coats and putting on your protective gear such as gloves and mask is time consuming also. You may want to consider one of the other finish types available. I like rubbed shellac under brushed on and polished Target brand waterborne alkyd/hybrid varnish. But there are many other choices for clear tough finishes that are less toxic and easier to apply than nitro.

  7. #6

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    I agree with Matt. There are better finishes for this application. However, if that’s what you want to use that’s fine but I’d recommend you just get some rattle cans of lacquer because an airbrush will take forever due to its small spray pattern and it will take a bazillion coats due to the amount of thinning you’ll have to do to get it to spray. It’s really hard to say how many coats you need without knowing the solids content and thinning ratios of your particular finish. With a rattle can you’d probably be fine with 5-8 good wet coats with at least an hour in between and wait at least a week before you sand it and buff it. If you use a sealer before the lacquer you’ll be on the lower end and if you don’t then you’ll be on the higher end of the number of coats you’ll need. Lacquer really is a colossal PITA.

  8. #7

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    Nitro was pretty much state of the art a hundred years ago, but there are far better options available now. Almost any option is better. I really like Tru-Oil, because it dries hard, it's easy to apply, and it's easy to refinish if it's necessary. And it won't destroy your lungs, or those of anyone who might be in the same zip code. The same goes for most of the available finish options, more or less.

  9. #8

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    All of this is true, but there is one great advantage to nitro, once applied - it's repairable. There are other aesthetic - or peceived aesthetic- advantages, but that has to be part of the reason nitro is still regarded as a premium finish. Poly isn't easily repairable, although it can be dropfilled, and once poly splits and flakes, it's a real PITA. I have tried waterborne 'lacquer', but found that it had adhesion problems.

    But yes, just for a pickguard, probably oil/ waterborne etc may be more practical and less dangerous.

    As for finishing a whole instrument, I suggest there is a reason that nitro is still hanging on in there. It's noticeeable that many luthiers still offer nitro finishes, probably partly due to market demand. And Gibson, of course.

  10. #9

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    1. Lacquer is solvent based and the solvents can do serious damage to your respiratory system - use a proper ventilator, long pants, long sleeves and gloves.
    2. Lacquer solvents are extremely flammable. Spray outside in calm wind free from dust in a well ventilated area away from sparks and flames (and anything that might create sparks or flame - i.e. no smoking, and don't use a rickety old fan for ventilation if spraying indoors (and you won't be spraying indoors for the next reason)).
    3. Leave your work outside for a bit after spraying or you're entire house will stink of solvents and lacquer. I've use sheets or a tarp for a 'drying tent' to keep my work dust-free outside for the first couple hours while the lacquer and solvents are out-gassing.
    4. Don't spray outside near your home's open windows or doors or up-wind of your home (see #3).


    I don't want to scare you off but when starting with nitro lacquer it's best to be a bit paranoid. After some testing shooting lacquer isn't too difficult.

    It's best to build-up lacquer with thin coats as the solvents will cause each coat to "burn in" to prior coats - the solvents in the lacquer you're spraying will partially melt the prior coats of lacquer. If you have dust spots or drips then wait until dry to lightly spot-sand and touch-up - you don't need to strip the entire piece to fix a blemish as the repair will "burn in" to surrounding lacquer.

    You'll want to wait up to 30 days for the lacquer to cure before final sand and polish.

  11. #10

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    A big thanks to all of you for sharing your valuable knowledge, and specifically also for your concern about my health :-).
    JN
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    JazzNote