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Modding Primer for acrylic plastic?

Discussion in 'Modding' started by Vault-Tec, 29 Jun 2016.

  1. Vault-Tec

    Vault-Tec Green Plastic Watering Can

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    Hi guys. So the other day I decided to paint the starter box for my cold cathodes. Any way, I sanded it down which made it smell like strong plastic then I primed it using acrylic primer and it came up with tiny bubbles/refused to coat in areas.

    It doesn't matter because it's only a starter and it'll be hidden but yeah, what's the best primer to use on acrylic sheet?

    I plan to make and paint a lot of cover panels soon so I really need to know what won't react and will seal the surface allowing me to use cellulose paint.
     
  2. hovek

    hovek “Can’t or won’t?” Sterling Archer

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    Did you clean it before paining? If it forms bubbles it usually a dirty surface, most likely grease.
    I use halfords standard grey primer and it works fine. Tamiya or Gunze would be better for more detailed surfaces (like scale modelling stuff).

    Also, what grit sandpaper did you sanded with?
     
  3. Vault-Tec

    Vault-Tec Green Plastic Watering Can

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    I sanded it with a scotchbrite pad thing. Just a scuff pad. I cleaned it thoroughly and used Acrylic primer, then Tamiya black spray paint. It was a reaction, not grease or anything like that tbh.
     
  4. Cheapskate

    Cheapskate Insane? or just stupid?

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    Tamiya is a model paint, so it's "low attack". I mean that it doesn't have a strong solvent mix like normal paints do. The styrene models are made from is easy to damage with solvents.

    What you want is an automotive etching primer. Bill used SEM on my Ion cube. It stunk forever, but it's indestructible. It fused to the surface permanently.
     
  5. David

    David μoʍ ɼouმ qᴉq λon ƨbԍuq ϝʁλᴉuმ ϝo ʁԍɑq ϝμᴉƨ

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    Vinyl Dye?
     
  6. Vault-Tec

    Vault-Tec Green Plastic Watering Can

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    Thanks for that :) I've ordered some plastic primer for now, didn't realise they made the stuff.

    Spreadie - Basically I am making my own PSU enclosure and a ton of cover panels for my rig using all of my old offcuts of completely different coloured acrylics. So I've got purple, clear plexi (not acrylic) yellow, orange black and white :S

    I've got the paint I want to use for the finish which is somewhere between flat and satin and I love the way it coats and the finish but I need something to go on first. Given that it's a mixed bag I guess I can use some offcuts to test with various primers :)
     
  7. InsolentGnome

    InsolentGnome Minimodder

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    ^this. Also don't be afraid to sand acrylic before painting. It's slick as snot and that primer coat needs something to grab on to. I'll hit it with 320 or 400 grit and make sure there's no shiny spots. 320 or finer will be covered by any decent primer and gives it some grip.
     
  8. phoenixck

    phoenixck What's a Dremel?

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    Specifically what you're fighting is mould release agent. You commonly get/notice on models just need to wash in warm soapy water. As you've already removed most probably with your sanding you could maybe get away with though wipedown instead.
     
  9. LennyRhys

    LennyRhys Oink!

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    I think you're onto something here. I've recently been casting a custom made part using polyurethane resin, and I'm having problems with painting because the resin gives off fumes that act like a solvent, and my paint has tiny bubbles forming in specific places just like you describe (I tried Revell acrylic paints first, and then Ambersil acrylic spray paint).

    It's possible that the acrylic sheet is having a similar effect on the paint that you're using, but I'm not really clued up on plastics and the chemistry of it all (huge subject).
     

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