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Modding Plastic painting

Discussion in 'Modding' started by Kronos, 8 May 2011.

  1. Kronos

    Kronos Well-Known Member

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    I am a little embarrassed to post such a basic question.
    I recently bought one of these http://forums.bit-tech.net/showthread.php?t=207557 as I intend to upgrade my PC which in effect means that my better half gets the older stuff, but this time I decided to give her a new case.

    I intend to cut a window in one side then have the two sides and top powder coated, she wants the case to be green and has chosen the colour RAL6024.

    To the main reason for the post the font of the case is plastic and although I have looked on line and have some pointers I am looking for the definitive help I know you guys can give. She is looking for a contrasting green for the case front. I am really looking for prep info, paint type, whether I need a primer and a clear coat?

    This is my first foray into case modding so again forgive me if my question's seem a tad naive.
     
  2. Smilodon

    Smilodon The Antagonist

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    What is there to be embarrassed about? Painting plastics is actually difficult to get right.


    The best way to do it probably with dye. It's more or less like a very thin paint made for plastics. It the only prep needed is a good clean with rubbing alcohol. The finish will be almost exactly like the original plastic, but in a different color (And maybe a bit more glossy). You must be careful when applying dye, though. It's very thin, so it will run very easily.

    The problem you have is finding dye in the correct color. Normally it's either black or gray, but maybe your local paint shop can help you out. (It's usually used for coloring car interiors)



    The other solution is to get some plastic primer and normal spray paint. Make sure you get primer specifically made for plastics. Normal primer doesn't work as well. You probably have to sand the plastic slightly to give it a key. On a front panel this can be a pain, though.
     
  3. Kronos

    Kronos Well-Known Member

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    Thanks 'smilodon' I was thinking along the lines of a primer and spray paint,what size grit sand[paper would you suggest?though I will be getting a mixed packet. Would I require more than one coat and if so should I sand between coats?
     
  4. Smilodon

    Smilodon The Antagonist

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    It depends on what finish you want to achieve. If you want the original texture you can't sand at all. The paint may not stick well, though.

    If you want it completely smooth, you start by making the plastic smooth. Normally 240 grit will work well on a normally textured panel. Then smooth it out with about 400grit. (To get rid of deep scratches, so you don't have to fill them with paint.

    Then you put on primer. Don't sand the primer unless it says to do so on the can. Proceed with color. Apply as many coats as needed to give a uniform color. Sand between each coat. Use a sanding block, and sand just to get the surface smooth. (get rid of the "orange peel texture", but immediately stop when that's gone). 800-1200grit will work well. Use it wet, and rinse it often in water. Higher grit paper is slower, but safer to use. :)

    If you paint with metallic paint DO NOT sand the last coat of color. This is especially important on metallics with large flakes.


    Then move on to clear coat. The process here is pretty much the same as with the color coats. If you want that super gloss finish you need to polish the paint after you are finished, but if you want to match the finish of the powder coat you should probably skip polishing.
     
  5. Kronos

    Kronos Well-Known Member

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    Thanks again. You have been more than helpful.
     
  6. IvanIvanovich

    IvanIvanovich будет глотать вашу душу.

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    other options are vht penetrating vinyl dye, which goes beyond the surface of the plastic, deep into the material. it comes in quite a few colors, but an exact match might not be available. you can often find it in auto parts suppliers.
    alternately you can boil the plastic in rit dye, which you might be able to color match by blending 2 or more colors via trial and error. at about $1 a packet, its a very cheap and effective way to color light (white, light biege, light grey) plastics. you can often find this is supermarkets / druggists.
    using either of these won't change the texture of the plastic, and won't be shiny either which may benefit. also both of these are 'lazier' methods, as no prep asides from it being clean are required, ie no sanding etc. but best of all is the durability. since it soaks into the plastic, scratching won't show the old color and there is no chance of it flaking or peeling off like paint.
     
    Last edited: 8 May 2011
  7. Smilodon

    Smilodon The Antagonist

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    I don't think rit dye works on "fat" plastics like ABS, though.
     
  8. IvanIvanovich

    IvanIvanovich будет глотать вашу душу.

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    yes it does, i've done keyboards with it.
     
  9. Smilodon

    Smilodon The Antagonist

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    Nice! Will have to test that out someday. :)
     
  10. genesisofthesith

    genesisofthesith complete spanner

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    Last edited: 10 May 2011
  11. Kronos

    Kronos Well-Known Member

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    Thanks 'genesisofthesith' that looks a distinct possibility.
     

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