Painting PVC: Clear Coat First?

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GimpyJohn
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Painting PVC: Clear Coat First?

Post by GimpyJohn » Tue Jun 16, 2015 11:13 am

Simple question, just don't know the answer: if you were going to use some pieces of PVC in a scratchbuild that was mostly composed of styrene parts would you first spray the PVC bits with clear coat (gloss or flat, either one) before painting?

Same question about plastic drinking straws, like you get from fast-food joints, or in packs of 100 from Kroger? With them, the main problem is that paint doesn't seem to stick to them hardly at all. Just handling them to glue them in place will sometimes cause the paint to flake off. I'd really like to find a solution fur this; they come in so many wonderful sizes, shapes, and lengths that they are almost indispensable to my kind of scratching.

Thanks for any advice, folks!
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raser13
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Post by raser13 » Tue Jun 16, 2015 12:19 pm

Adhesion promoter?vlike what they use for car bumpers. That what you have to use to paint a lot of toy parts like the hasbro falcon. It sticks to almost any plastic. Don't. Know never used straws. To flimsy.
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kenlilly106
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Post by kenlilly106 » Tue Jun 16, 2015 12:38 pm

For PVC olymbing parts of scuff sand the surface before priming, the parts have a surface treatment that helps with fliw and prevents sticking. For other PVC parts you should be ok as long as the surface isn't super shiny or slick.

I've painted whithe plumbing parts after scuffing with auto lacquer primer and it works fine and bonds very well.

Straws are either polyethylene or polypropylene, both are known for being unpaintable and generally non-stick.
Your best bet is to paint them last and minimize handling them after painting if you use them.

Ken

GimpyJohn
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Post by GimpyJohn » Tue Jun 16, 2015 2:26 pm

Both of you gentlemen have given me excellent advice. Thank you boyh, very much.

Raser, I have another question: I have never heard of "adhesion bonder". Where does one find it, and do you recommend any particular brand name? Ken's point about just handling straws less to avoid paint-loss is exactly my experience in the past, but I'd love to find an alternative to it. Sometimes it isn't possible to avoid "handling" them to some degree, because they are often used in such a way that they must be attached/glued earlier in the build, rather than later.

And yes, I agree, they are quite flimsy. But, man! if you can make them work, they can solve a lot of problems. One way to de-flimsy them is to use small wooden dowels inside them. I'd just as soon use the dowels themselves, and skip the straws, but I've never been able to hide the fact that-- despite all my efforts-- wood looks like wood. Not exactly kosher on a starship. :D
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SCI-FI
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Post by SCI-FI » Tue Jun 16, 2015 3:06 pm

My current can of adhesion promoter is from DupliColor, purchased at a local auto supply store. It goes on like a very thin coat of clear. No long-term test results to report, though, as I just bought it s few weeks back...

GimpyJohn
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Post by GimpyJohn » Tue Jun 16, 2015 5:48 pm

Hey, cool, Sci-Fi! I understand that you haven't had it for long, but does it seem to work okay to you, so far?

If you don't mind me asking: what did you use it on? Anything normally resistant to paint?

Now that Raser and you have me turned on to it, I'm extremely hopeful! Straws and PVC aren't the only things I have around the house that I would cannibalize and use in scratchbuilding, if they liked paint better!
"There she is! And not so wounded as we were led to believe. So much the better."

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Post by OdysseySlipways » Sun Jun 21, 2015 12:11 pm

why use the bumper primer? i would just use a regular automotive primer, just make sure you don't grab the sanding primer as it's be thicker and have a rougher texture to it.

i use regular auto primer for everything, plastics and metals, non of that water base primer here
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SpaceRanger1
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Post by SpaceRanger1 » Sun Jun 21, 2015 4:04 pm

You can also try using a dilute solution of white glue. This was the recommended primer for Airfix's polyethylene figures and tank treads back in the old days.
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OdysseySlipways
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Post by OdysseySlipways » Sun Jun 21, 2015 9:23 pm

i would think that would crack/crumble/break-up after a while
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