wet sand paint ? or no?

Discussion in 'Guitar Building' started by theMIDrange, Feb 26, 2016.

  1. theMIDrange

    theMIDrange Member

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    Let's say you're doing a solid color. You probably wet sand between applications? but on the last spray, do you wet sand that as well or just leave it to dry a couple weeks prior to clear nitro over top?

    I've been wetsanding to 2000 prior to clear, but cannot get rid o small swirl marks which wouldn't be there had I not wetsanded the last paint coat...but then it wouldn't be the correct look I don't believe. I seem to want to wetsand the last paint coat..

    any ideas?
     
  2. Michael_P

    Michael_P Member

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    swirl marks?

    you mean orange peel?

    to me, swirl marks are what is seen as a result of many types of polishing gone 'wrong'.

    anyway, with lacquers, many times sanding between coats is not required...why? because lacquer's solvents eat into the previous coats and bonding occurs creating, for all intensive purposes, a continuous product even though it's multiple layers of application...your statement of waiting a couple of weeks until clear would be a case where you would need to sand before applying...if you applied clear within, IIRC, 3 days, sanding would not be required...

    please be aware that I am making statements as pertaining to a non catalyzed product...air dry lacquers take around 30 days to reach good curing, and there are different rules as to how one approaches time between coats.

    the big picture is that it's the smoothness of the clear coating that makes the difference...one will of course be wet sanding and polishing that layer to make it shine like a show car!

    as long as you don't sand through the clear and get into the color all should be grand...if you nick the color, then you are hosed, and this would be an argument in favor of sanding the last color coat...
     
  3. theMIDrange

    theMIDrange Member

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    I just use cheap black hardware store paint. It ends up looking great, I just want to try and dial it in more. So by swirl marks I mean just marks due to sandpaper (ended at 2000 grit).

    There is a touch or orange peel as well but it's not too big an issue....actually like you say the clear is probably more key. I've done this on past projects and most the swirl disapperas under the clear but I thought i'd inquire to see about possibly improving this time.

    so it sounds like wet sanding the paint is not a common practice.....I do it because it seems to give a good end product. But then again i've never Not wet sanded the paint so I don't know how better or worse it would end up non wet sanded.

    I also lightly relic the end product so I really don't need the ltop level job most need. but the small sandpaper swirl marks would be nice to totally remove. I'll try a 4000 grit
     
  4. pshupe

    pshupe Member

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    Generally colour coats are so thin that you do not sand them. Wet sanding is for leveling. I do not even wet sand until my final coat of clear. I've only sprayed bursts so do not know whether building colour coats helps in anyway. I can't think of why it would. One coat of an opaque colour should get you where you want, correct? Then you build up clear on top of that. a lot of people sand in between a certain number of coats of clear, but again that is to level the surface so you don't end up having to sand a ton to get a level surface on your last coat of clear, after curing.

    Regards Peter.
     
  5. 87hdrush

    87hdrush Member

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    this link is about color sanding cars. IMO the process is the same for hand rubbed lacquer. You can tell the difference in the depth of the finish if you color sand before spraying the clear. small difference but noticeable. Color Sanding - Wet sanding or Color Sanding ?
     
  6. Michael_P

    Michael_P Member

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    color sanding also can affect the color depth...

    upon reflection, I would have to say you'd want to level sand the coat before your final color then shoot the clear if possible...

    if a metallic paint is being used, then definitely NO sanding of the final coat as that will mess with a lot of things...
     
  7. TKOjams

    TKOjams Well-Known Member

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    What type of finish are you using? Lacquer, or Poly?
     
  8. 292fan

    292fan New Member

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    the link that 87hdrush posted is pretty spot on for most any finished paint, especially if your using an enamel sprayed out of a professional paint gun, if using spray bombs be very careful not to burn through the paint, its very easy to burn through, spray bombs tend to be thin coats, and in some cases produce what is called dry spray,the paint is mostly dry before it hits the painting surface, causing an effect that looks like you painted right over dust. careful wet sanding, followed by a cut and buff can produce in incredible looking finish even with spray bombs,lots of even coats is the best method I've found for spray paint, light wet sanding( 2000 grit or finer) in between coats just to smooth out the imperfections( runs, dips, dry spray etc), my method is primer however many coats it takes to smooth out the body, sanding between each coat until body is smooth, then base color, 4 or 5 coats, sand out imperfections, then clear coat, 10 to 15 coats, I like to bury everything under a heavy clear, sanding out imperfections in between coats, after allowing to dry for a couple days, I then final cut and buff, using professional grade swirl remover and buffing compound, usually 3m brand. if using multiple color(for graphics or patterns) use the same method as the base color then apply the clear. if using stickers or any kind of adhesive attached graphics, be sure you check that the adhesive material, wont react to your paint of choice. other wise the out come can be very ugly, and possibly equal stripping the surface all the way down and starting over. same goes for the primer, base colors, and clear coat, always use the same brand, if not possible, read the can and match up the solvents.
     
  9. theMIDrange

    theMIDrange Member

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    so I'm into my black spray can paint gibson......I read that link. thanks. that was a good explanation. I learned that color sanding is wet sanding paint and 'wet sanding' is wet sanding the clear post paint. So that term I was not aware. Makes sense now

    But

    I've got several coats paint on, looks good. I have been color sanding until last coat which is pretty darn nice and I have not color sanded this last coat YET....What I don't understand is this. When I leave the last color application unsanded, it is glossy (using basic black gloss). It does have a bit orange peel. The orange peel can smooth out when color sanding but when I color sand it looks satin and not gloss. The article is saying colorsanding results in more and deeper compared to just wet sanding. I guess the gloss I see now when leaving last coat non color sanded has nothing to do with end product. Color sand then clear then wet sand will result in more gloss correct? even though when at color sand step, it deglosses.....? yes.

    I am at the point where I can choose to color sand my last coat and smooth orange peel or leave orange peel and go to clear stage.......this door panel looks like what I get when color sanding. Clearly it dulls the entire thing, but apparently this is natural. https://www.youtube.com/watch?v=5hzQyaRof4k

    but in the next vid he used 2000 grit and 4000 and it starts to polish and not dull it like 1000 did. then the paint is buffed and THEN it is cleared?

    This is where i'm unsure. Is that correct? Is the paint wetsanded and buffed all prior to clear? and then clear is applied and again buffed?

    It's still not clear. Should the paint look hazy or clear right prior to clearcoating?
     
    Last edited: May 25, 2016
  10. bmac6502

    bmac6502 Member

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    Everyone does it differently. It depends on your approach and the product you use, you just have to develop your own strategy to some extent. Some don't do much sanding until the very end. Others sand between every coat. The basic principle is just to keep every coat as level as possible without sanding through, and only aggressively sand and buff the final coat. Not the final "color". I mean the *final* coat - the very last thing you spray. There is no point (and probably some harm) in buffing before the very final coat. Don't worry that previous coats look dull - unless you leave visible scratches in them, the next coat will fill in over the top and make it look seamless. The gloss all comes from the very top surface.

    The glossy finish is all done at the last coat. If you are spraying clear, spray all the clear. You can sand at least a bit between coats if your orange peel is too high, but your goal is just to try to give a mostly level surface for the next coat to lay down on top. After you are all done spraying, sand all the way out to at least 2000, higher if you want, and then you can buff. The higher you go, the less you need to buff.

    It feels counter intuitive - when you spray it looks glossy, but with a little orange peel, and then you have to sand it out dull. It feels like you were really close, and then ruining it on purpose, but that's what you have to do. At the end, when you have a completely flat, smooth, but dull surface, the buffing of the top coat brings out the glassy surface.
     
  11. Michael_P

    Michael_P Member

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    what he said...buffing will leave contaminants on the color coat...it's the clear that is going to make it shine deeply.
     
  12. theMIDrange

    theMIDrange Member

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    so, I decided to color sand the last application color and again, it smooths out nice and level but there where scratches behind 2000 grit....so I added a touch buffing compund and with a micro fibre towel, hand washed the last color coat. for some reason this easily and quickly disappeared most scratches and it looks nice. I did this on the previous coat as well and put the last color over it. I was concerned that little bit of buffing compound would cause problems with paint sticking but it didn't. So I imagine that little bit of compound on this last coat will not cause issues with the clear going over it?
     
  13. 292fan

    292fan New Member

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    the reason the buffing compound takes care of the tiny scratches that you are seeing, is because it is a much finer abrasive then the 2000 grit paper, so well it is still the same concept as the sandpaper, it is on a small enough scale, that instead of seeing scratches and dull paint, it starts to bring out the luster or shine of the paint, and when done correctly on the top coat/final coat of clear it can make it look like glass. as to your last question, I have no idea if it will react with your clear, in theory as long as you have removed all of the compound off of the guitar body before spraying the next coat, which if your hand washing the body, you should be fine. if you wanted to be absolutely sure, you could give the paint a couple of days to cure, and then pick up a product called Prep-all [ame]http://www.amazon.com/Kleanstrip-GSW362-Grease-Remover-Gallon/dp/B008QDSVPE/ref=sr_1_1/187-4238751-7581751?ie=UTF8&qid=1464273326&sr=8-1&keywords=prep+all[/ame] it and similar products are used by painters to remove any and all contaminates that may be on the paint that could cause a reaction. then after wiping down the body with the prep-all(it will evaporate off the guitar), start applying your clear coat, it can take a lot of work, but after the first time you get the cut and polish right and the final product looks like a mirror, you'll be hooked. and even if it something does go wrong, its only paint.
     
  14. theMIDrange

    theMIDrange Member

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    thanks for the link. I wonder if a little dab or two of lighter fluid could be substituted to help evaoprate/clean any polishing residue? Because I have that handy at the moment.....but I agree, this colorsanding looks to be worth the effort....

    so my individual best practice routine at this point, trying to get good results with cheap spray paint and a minimal sanding setup is:

    one coat primer, several coats paint, colorsanding each time. The last paint application gets a bit of polishing compound and buff. Then a wet wash and/or residue clean (using an evaporative product). Then nitro clear (stemac rattle can). This clear gets same polish treatment as paint colorsand did.

    I will wait 4 weeks to let paint dry prior to clearcoating.

    Other tools are 400-2000 wet dry paper, a small sanding block. simple and cheap. Starting to get results compared to the dozen other guitars i've painted similarly. The knowledge of what colorsanding is compared to clear wetsanding is the new piece to my system.......yes ideally one should use a hplv sprayer, quality paint etc. But money's tight so this setup will have to work.
     
  15. Michael_P

    Michael_P Member

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    if you wait 4 weeks to clear coat you will need to scuff the finish with sandpaper...this is just a simple rule of lacquers...and if you're not using lacquer, it is a NECESSITY...

    lacquers melt into the previous coats by solvent reaction...but, if 3-5 days have passed, it's a rule to scuff the previous coats...this opens up the finish to solvents still in there, but deeper down...hard to put into words, but I get the gist of the rule...

    with other finishes, the scratches give a mechanical bond for the next coat to grab into...

    either way, buffing the color coat was a waste of time pretty much...no reason in the world to do so...if you had sanded to 2000 and then started spraying clear lacquer within 3 days you would have been golden...and as noted if you're not using lacquer then scuffing with at least 220 grit (or dull 220 grit) is rather required for adherence...

    I've shot over 50 gallons of lacquer in my life and am rather familiar with its characteristics...other finishes, no...best knowledge I can give about that is the following: been a carpenter for years...part of that job is doing hardware, which entails putting chisels to painted woods...one builder I deal with has painters that are using 320 grit sandpaper between coats and get a real nice, smooth finish..problem is those coats don't bond worth a flip...when I have to chisel in even a square corner for a pre-routed strike plate on a jamb paint goes flying every where...and I'm talking about a chisel sharp enough to shave the hair off of the back of my hand...yet other builders have painters that, while their final product is not so smooth and 'perfect', have used 220 grit between coats and I have very little to no issues chiseling into...point being, scratches deep enough to allow a good mechanical bond are required for paints (and yes Dorothy, clear is a paint) that don't have solvent reaction tendencies like lacquers
     
  16. theMIDrange

    theMIDrange Member

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    thanks much. basically i'm trying to get results with low cost and moderate tools.....even with many years experience it is a task when $ and tools are low! It's pretty close to pro imo Good enuph 4 rok n roll.....it will be naturally relic'd in no time anyway!





    [​IMG]

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    real happy with these results
     
  17. 292fan

    292fan New Member

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    and in the long run this is all that matters.
     
  18. Michael_P

    Michael_P Member

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    look, not trying to hound you or anything, but being happy with the results is a relative statement...

    when I'm doing a new finish job (please note, I'm a carpenter with 30 years experience, not a painter...I do it now and again, but it's still a bit of a mystery to me, that being qualified pay attention to this) I do a test panel...desired stain, or not, and finishing schedule with chosen product...

    then I test said panel...hit it with a hammer a few times...what I desire to see is ideally the finish bending into the dent and not flaking off or somesuch...rub the ribbed bottom of a beer bottle on it and observe the effects...and finally try to take the finish off with my thumb nail...if my thumb can take the finish off it's cr@p...and that is what I worry about if you don't properly scuff the finish before your clear coats...

    relic'd is sooooo relative...any scratches in the color coat will disappear after clear (well, unless they're divots the size of the Grand Canyon) and what you really want is to sand and buff the clear to a showroom shine, neh?

    but hey, if you want the look of layers of clear falling off and that makes you happy, then go ahead...

    using rattle can technology for your finish is not an issue...let's be real here...when you take the time to wet sand and then polish, then a rattle can compares to any other method...

    said other methods, and yeah I have a nice Binks Mach1-SL HLVP setup running off of a pressure pot, are more for production environments...in a guitar factory, higher efficiency of getting product onto guitar and less waste of product floating away...in the field, where you don't wet sand and polish, a smoother final coat which means a lot...

    again, if you're going to take the time to wet sand etc., the rattle can ain't a bad way to do! yeah, my system cost a fair penny, and that was acquired for an in the field project where not only did I do the wood work, I also did the finishing...at that point in time I had a Binks 2000 high pressure setup, and considering the cost savings of paint to be used on that project, the Mach1 paid for itself by it's efficiency...simple math...and a better finish too boot!

    point being, I get your penny pinching...and totally appreciate it...no issues here...

    BUT...there are schedules to finishing, developed by simple logic (understanding the 'rules' of the game) and experience...
     
  19. theMIDrange

    theMIDrange Member

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    maybe with a higher quality spray paint i wouldn't need to colorsand. But i'm using $1 cans and it just does not go on well enough on its own. Once its color sanded it looks nicer. I understand small scratches may disappear post clear. But the last coat, to add a small polish on a microtowel only took one minute and it really made the paint almost look like a mirror. it looks like it's got a bit o clear already. I still color sand each application as well (about 3-4 sessions o paint).... In any case i've been using these $1 cans about 6 years and this is the best results i've gotten to this point.

    I also tried a $6 can and it did not go on any better, just thicker and ran no matter how light application, so i've build my technique around these articular $1 cans and I guess like the other poster mentioned it's all about the particular materials and procedure that gets results in each individual case. I've got a white V using same paint in process and will post pics. Getting results on that one as well ....although the black is the one that really shows up scrathes post 2000 grit. Can hardly see these same scratches in white....
     
  20. Fret Hopper

    Fret Hopper Member

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    Just my.02. I sprayed a body with primer, level sanded that, then shot color which came out looking flat. No gloss what so ever.

    Shot about 4-5 coats of clear and it looks just beautiful. Depth and gloss like I never expected. Follow the steps they have laid out for you above and you will amaze yourself.

    From the ozone...

    Mark
     

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