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Sanding Finish

Discussion in 'Luthier's Corner' started by nikolozj, Jul 14, 2012.


  1. nikolozj

    nikolozj

    Dec 15, 2011
    Hi everyone!

    I'm working on my Ibanez Roadstar II bass already 3 months now!

    I already applied paint on it, waited 3-5 days and now I'm sanding down the paint, before I apply lacquer and polish it.

    I need just some advises, about how clear the surface should be?

    here are pictures:

    1585nah.

    MOSTLY it has some sort of this mat surface, not quiet MAT when you touch it, but it has this look of mat.

    BUT! there are also some spots where it's very glossy, probably because I sprayed those spots from shorter distance.

    like this spot at the edge here:

    33ljfqc.

    So what should I do, can someone suggest?

    Problems I see:
    1) The MAT look of the surface, which I don't know if will look same after lacquer (maybe it's fine?) and also I'm afraid to sand through.
    2) Should I sand these glossy spots as well, that's on the second picture or should I leave them?

    :help:
     
  2. Keep sanding, you're not there yet. The surface should be COMPLETELY level and matte (like the matte areas you have now). The surface is level when ALL the shiny spots are gone. Btw, it's best if you use wetsanding. I use a 600 grit (European Grit that is ;)) sandpaper which I soaked in a bowl of water with 1 drop of liquid soap in it (so the surface tension of the water is broken, and the sandpaper doesn't clog up when sanding). And you must use a sanding block, so you will sand even, if you just use your fingers, you'll sand through some spots, while others are still bumpy. I made my own block by cutting a sponge into a small rectangle, which I could manipulate more easily in the tight corners and curves.

    The matte surface will look nice after respraying. When done sanding, clean it with a humid rag to get rid of all the tiny dustspecs and impurities.
     
  3. nikolozj

    nikolozj

    Dec 15, 2011

    Thanks for the reply!
    I'm running out of 600, but I have bunch of 800, I guess it's okay?
    So is that surface in the first picture ready for lacquer to apply?
    It doesn't need more sanding.. like I did very fine sanding before paint, on sanding sealer, it was like a mirror:

    s1ji3b.

    I read a lot that sanding sealer needs very fine sanding but I never read anywhere how much sanding does paint need.....
    Paint doesn't need that much fine sanding?
     
  4. 600 is the max for me (don't go any coarser, 800 is finer, so that's just fine)

    When spraying over paint, the sanding makes sure the next layer adheres nicely on the previous (not true for nitro, as those layers actually melt in eachother). When I clearcoat, I tend to go for the same sandinglevel as you have on your primer. You can spray on the paint in this state, but for some peace-of-mind, I should go for an even undercoat in terms of level. The shiny spots are actually tiny dents. The flatter the surface, the less sanding you have in the end, and the more easy the buffing will go.
     
  5. How many sheets of 600# have you used so far? I can get a whole car sanded with only two sheets.

    Sanding is the worst part and the most important part of the job. If you stop early, it'll look like you left some fried eggs on the surface and painted over them.

    Flat sand and/or shape-sand but ALWAYS with a support that is not human hands.

    I use the standard and the longest flat 3M rubber blocks:::

    [​IMG] SandingBlock.

    ............and sometimes I use a 17" long dry board. That's not a real 'board' but a tool that's designed for panel sanding:::

    [​IMG]

    Use a firm closed cell block of foam for those curved and negative areas - resist using your hands or fingers. 3M also makes them (why not?):::

    31KoK6t8N3L._SL500_AA300_.

    Get a full-haze surface on the undercoats and you'll do better in the end.

    And about your choice of wording here: "So is that surface in the first picture ready for lacquer to apply?"

    Are you using a lacquer-based undercoat? If so - and you're in the same brands here - you might be OK. Prolly not, since I detect a certain amount of n00b in your question(s).

    'Lacquer" has illogically become a generic catch phrase for all paints that shine. In reality, it is a type of paint.

    The solvents and vehicles are designed to work "as a lacquer product" although for a while acetone/solvent based paints were coming into vogue and I really liked them.

    Unfortunately these had a short life in the Cal-ARB's view and water-based paints then took over.

    In digression: Lacquers can usually ONLY be applied over other lacquers, never over enamels (even very old ones) and in some situations it cannot be used over two- three-part catalyzed paints.

    You may be in Paint Hell here. What you need to do is categorically state WHAT paints/solvents/thinners you are really working with.

    And remember that you should not even mix brands of paints, as they are usually incompatible.
     
  6. Hi,

    I've just refurbished my 1983 Schecter P bass after having it for 26 years. I sanded back to bare wood, then used methylated spirits (called de natured alcohol in the US) to remove all dust, etc. I coated in clear polyurethane and let dry for 24 hours before sanding. I started out with 800 grit paper for the 1st coat, then gradually worked up to 2000 grit wet and dry paper in between each coat, followed by metho ( de natured alcohol) before re coating. I put on about 10 coats and the finished off with 2000 grit and metho, followed by application of auto polish, buffed.
    Hope this helps, make sure you get the surface even. Good luck!
    Photo at a8190cea.
     
  7. nikolozj

    nikolozj

    Dec 15, 2011
    SurferJoe46
    Thank you for so many advises!

    I'm from overseas, and because of a lot of differences between standards, brands, terms and basically in everything, I'm having a lot of difficulties understanding many things about not only this particular job.... and many information sources are from U.S. For example, a lot of sources I read used Krylon brand sprays, which I never seen in my life here.

    In 'lacquer' I mean very final coat of clear spray that will protect the base paint.
    I'm using this brand of spray:
    http://kventerprises.net/wp-content/uploads/2012/03/Aerosol-Spray-Paint-PDS.pdf

    It says that it's Synthetic Resin based.
    So far, I haven't found any other kind of information than this about these sprays. On the cans it doesn't say anything but the instructions of how to spray in different languages.
    I'm thinking of using clear spray that this brand has as a 'lacquer', final coat that I'm gonna polish. Here, the local market people call it "nitro lacquer", however, I don't think they have any idea if it's true or what it means. Me neither!
    I've just been trying to somehow use the same things that I read and things I read is not the same as here by means of terms so I'm lost in terms sometimes and yes I agree with this :

    I am :(
    I'm doing it first time. Started 3 months ago, thought it was a cool idea, but now I just want to finish it, not enjoying process anymore. :/

    Mr.Fingers
    Yeah.. I already noticed that.. it's like a hell, you get punished on final sandings for the sins you've done while painting.... should have known that!

    What's the best thing to do after sanding through?

    toughluxury2010
    Very nice!!
    Mine is P too.

    I thought about natural wood, and not color-painting it... but the body is not one piece so I changed my mind...
     
  8. radiojunkie

    radiojunkie

    Jul 15, 2012
    mid-atlantic
    suffers from chronic lyrichosys
    I've never sanded lacquer between coats, only enamel. Lacquer sands sticky, enamel sands clean.

    Besides, fresh lacquer virtually melts the surface of the existing coat. IMO, sanding isn't necessary for lacquer, especially if it's applied in multiple, light coats. The end result is like one thick application.

    IMO, the difference in your textures is application. The glossy spots are direct hits and the less than glossy spots include overspray. Overspray isn't runs, it's when paint partially dries before sticking to the surface. You may have had the paint valve too far from the object or your spray motion may have been too fast. IMO, overspray is much easier to prep and respray than runs.
     

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