Frosting clear test tubes - suggestions?

Discussion in 'General Modeling' started by halforc80, Jan 14, 2012.

  1. halforc80

    halforc80 New Member

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    Hi all,
    Fairly simply question I hope; I'm using some plastic/acrylic test tubes in a build and want to defuse LED light through them, which I'm hoping frosting the plastic inside the tube will achieve. While I can find loads of advice on frosting clear plastic sheets, I'm at a loss as to how to frost the inside of plastic tubes...

    Any ideas, oh model builder massive? :)
     
  2. who45

    who45 Well-Known Member

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    if there plastic some wet and dry paper would give a frosted look and be smooth on the fingers - i used this technique on a clear block of perspex as i needed to frost it - it worked a treat - so sanding down the exterior of the tube should give the same effect

    think i used 400 and 800 grit paper and to really smooth the finish i hit it with 1200
     
  3. robn1

    robn1 Master Member

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    If you want to frost the inside, try clear flat paint. Or sand/media blasting if you have the equipment. But if it's the inside clear flat will do, and can't be rubbed off from outside.
     
  4. cayman shen

    cayman shen Master Member

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    Maybe fill them halfway with sand and shake them a lot?
     
  5. feek61

    feek61 Sr Member

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    Rustolium makes a "Frosted Glass" spray. It works pretty good.
     
  6. robn1

    robn1 Master Member

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    Spraying the inside would be difficult. Use a bottled clear flat like Tamiya. Pour some into the tube and swirl it around until the whole inside is coated. Then pour out the extra. You can do multiple coats until you get the level of frosting you want.
     
  7. halforc80

    halforc80 New Member

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    Cheers all!
    I've got a bunch of tubes, so I'll experiment with both sanding and the clear flat paint method. Hopefully, I'll get a good effect from one of them and a good defusion of light leading to a nice glow afterwards! :D
     
  8. Gigatron

    Gigatron Sr Member

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    Get a long, wooden dowel, smaller than the inside diameter of the tube (but only by a few fractions of an inch). Spray the dowel with spray adhesive (some 3M 77 should do well) and attach sheets of sandpaper (rubberband them on, overnight, to get good ahesion). Chuck a decent sized bit into your power drill and drill into the dowel - voila, instant, powered sanding rod.

    -Fred
     
  9. T2SF

    T2SF Well-Known Member

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    sand blasting or spraying is the best way to get a nice even coat very quickly.
     
  10. Scratchy

    Scratchy Well-Known Member

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    I have a small hobby sand blaster, the size of an airbrush. It would certainly do the job. If I can just find some way of passing it through this computer screen to you, then your problems would be solved.
     
  11. Scratchy

    Scratchy Well-Known Member

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    What about steel wool? Was that mentioned....
     
  12. T2SF

    T2SF Well-Known Member

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    It will leave an uneven/ non uniform finish, I would try 600+ grit sand paper but perhaps do a test of different tricks ;)
     
  13. Darkside

    Darkside Well-Known Member

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    can you test a small piece with acetone?
    i reacts with surface and could give this effect, if the material is strong enough it wont be cracked or destroyed. but a dilute solution (in grain alcohol or methanol) could do it.
     
  14. Jayn

    Jayn Sr Member

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    if it's straight sided , maybe a piece of vellum/tracing paper, or theatrical diffusion gel cut to fit the inside? that would work if there's no round bottom to the tube..
     
  15. Scratchy

    Scratchy Well-Known Member

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    Why not try pouring a bottle of liquid cement into the test tube, then pour it back into the glue jar. This stuff fogs plastic windshields on models, .... why not make it the technique to frost the acrylic test tube?
     
  16. Conqueror_Worm

    Conqueror_Worm Well-Known Member

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    I agree with Darkside. I once used an acrylic pipette with acetone, it created a very nice frosted effect...
     

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