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Thread: Panel prep after plastic media blasting before epoxy primer

  1. #1
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    Default Panel prep after plastic media blasting before epoxy primer

    I am getting a car media blasted with plastic media. I have read that for sand you can just wipe down the car with wax and grease remover and then spray epoxy primer. But I haven't found much info for plastic media. Is it the same? I was worried that the plastic wouldn't leave a good enough "tooth". But I REALLY don't want to sand the whole car down. Any thoughts?

  2. #2
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    Quote Originally Posted by fusion_ View Post
    I am getting a car media blasted with plastic media. I have read that for sand you can just wipe down the car with wax and grease remover and then spray epoxy primer. But I haven't found much info for plastic media. Is it the same? I was worried that the plastic wouldn't leave a good enough "tooth". But I REALLY don't want to sand the whole car down. Any thoughts?
    As long as you can blow it off and wipe it down with grease and wax remover then prime it with a good epoxy primer right after it's blasted you should be fine. The trick is not to let it sit too long before priming.

  3. #3
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    Quote Originally Posted by Len View Post
    As long as you can blow it off and wipe it down with grease and wax remover then prime it with a good epoxy primer right after it's blasted you should be fine. The trick is not to let it sit too long before priming.
    have you done a car that's been plastic blasted before len? i have zero experience with that.
    after going through the trouble of blasting i wouldn't hesitate to take the time to sand before epoxy. if there's no paint on it it wouldn't take long at all.
    b marler

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    Quote Originally Posted by bmarler View Post
    have you done a car that's been plastic blasted before len? i have zero experience with that.
    after going through the trouble of blasting i wouldn't hesitate to take the time to sand before epoxy. if there's no paint on it it wouldn't take long at all.
    I've done panels but not an entire vehicle. You're right a little scuffing might make epoxy hold on better but you could also use a good etch primer and their would probably be less need for scuffing. Some epoxy primers have an acid mixed in so you get a little of both benefits.

  5. #5
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    It depends on what plastic media they used. Plastic media comes in many grits/grades which are denoted by their color. Most plastic media blasters use a combination of colors/grades which depict an all around experience for the surface being blasted, i.e. aluminum vs cast vs steel. Generally speaking plastic media needs to be abraded before epoxy primered in terms of auto refinishing as it is the focus of the blaster to not harm your metal surface unless you request a specific tactual surface as to go straight to epoxy. In which case I personally would not use plastic media, however if your build has some serious rust and you are trying to conserve as much of the original metal as possible this is a good route.

  6. #6
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    Thanks for the replies thus far. If I were to sand, would a Scotch Brite hand pad be enough as just a scuff or would I need to sand with a DA? If so, what grit? BTW I am using Omni epoxy primer.

  7. #7
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    Quote Originally Posted by fusion_ View Post
    Thanks for the replies thus far. If I were to sand, would a Scotch Brite hand pad be enough as just a scuff or would I need to sand with a DA? If so, what grit? BTW I am using Omni epoxy primer.
    If I were sanding on the metal before priming I'd probably use 220 or 320 dry paper either by hand or on a DA.

  8. #8
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    Quote Originally Posted by fusion_ View Post
    Thanks for the replies thus far. If I were to sand, would a Scotch Brite hand pad be enough as just a scuff or would I need to sand with a DA? If so, what grit? BTW I am using Omni epoxy primer.
    i'm with len, hit it with a da and 220. only take a few hours. scotch brite isn't going to do it.
    b marler

  9. #9
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    Len and bmarler give you all the info you need. I personally use a combination of 220g dry hand scoffing (areas where DA cannot reach surface by hand abrading) and 180 dry on a DA for rest of surface. I have no doubt you can scuff with 220- 320 and be just fine, I just like a little more mechanical grip.

  10. #10
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    Default read the epoxy directions...

    Here is an example, PPG Epoxy recommends P80-120 for bare steel. If a DA isn't in the budget or your compressor won't put up with the air consumption, use a quarter pad sander from the local box store.
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