Thread: painting plastic
05-08-2007, 10:15 PM #1
- Join Date
- Apr 2005
- San Diego
Im looking to paint my hood, what do I have to do as fars as sanding goes has anyone have experience with painting plastic? I have a can of that chameleon paint and would like to add a custom look.
05-09-2007, 09:38 AM #2
I used to work in bodyshops for 8yrs and I painted cars and many plastic parts during that time and for "side work".
Plastic requires certain attention that metals do not. There are "releasing agents" in plastic parts that allow them to pop out of their mold once poured and baked. These agents will fight against a good adhesion and is why you may see repaired bumpers with paint jumping off the surface with shody prep work.
To remove these releasing agents, you could buy some expensive professional paint materials from shop suppliers (etc etc), or you could go the easy way which is just as good surprisingly enough ---> buy some Comet cleanser and rubbing alcohol. For the price of $3, you will be able to scrub down the plastic with a scoth pad with these products.....
Use them alternately ---> Comet with scotch pad and warm water (warm is optional but helps with cleansing)....let the part dry either by sun or hairdryer. Then use rubbing alcohol to give it a bath. These 2 products are great for pulling the agents out. Use each product at least twice.
Once done, then you can sand them with a modest grit for mechanical paint adhesion (about 320-500ish). Once done with the sanding, reclean the parts with Comet and alcohol again with a clean scotch pad....rinse the Comet off (or dry the alcohol - whichever you used) and then use sunlight or hairdryer to confirm that the dampness is completely gone from the plastic.
Meanwhile, at this point, do not touch the exterior side of the part with your hands. Your hands can leave oils even when you think they're clean. Spraypaints can be sensitive to contaminents. Set the part up on a clean sheet of lint-free paper (or similar) and begin painting.
If you have any humidity in your area, keep the hairdryer on hand to use between coats and "dust" the part with some heat, but dont get too close for too long. This will keep the paint from "blushing" in the event that the humidity is high or that you spray the paint too thick.
Spray even, semi-damp coats and let flash for a few minutes between.
I'm assuming you're using spraypaints (??).
Let me know if that covers it for you,
05-09-2007, 09:21 PM #3
- Join Date
- Apr 2005
- San Diego
Thanks sean for taking the time to write all that, very much appreciated
05-09-2007, 09:30 PM #4
- Join Date
- Oct 2005
Hey moderators, this might be a good one to move to the "How To" section.
05-09-2007, 09:57 PM #5
what about using adhesion promoter on plastic parts to keep em from blushing, fisheye etc. Works good on my car interior parts.
05-09-2007, 11:17 PM #6
Well adhesion promotors and fisheye removers aren't for avoiding blushing. Those are pretty mush specific-use products for what they're labeled for.
Blushing is dampness getting trapped in the paint and becoming milky looking. If you spray too heavy, humidity could get trapped (if it's high humidity to begin with). If you dont use heat right away (sun/hairdryer) it could get trapped permenantly, and need a sand and recoat.
But ALONG WITH the Comet and alcohol, if adhesion promotors can be used (with air guns etc), then awesome, go for it. I've heard some bad things about "Bulldog". I've used it but never personally came across adhesion trouble. Others (who are also professional painters) have.
Another cheap and easy way to ensure adhesion (if you're using spraypaints) is to use the Krylon "Fusion". That stuff is supposed to be tough enough that it doesnt even require any prep other than cleaning! I've used it ALONG WITH a good prep (as usual) and it was very nice to use. A friend actually bent the **** out of a part with Fusion and it didnt even stretch or crack. I used it on a plastic cowl piece on my supra and it's been looking great for over 2yrs now.
Never any excuse to dodge a good prep with the readily available products like comet and alcohol. That stuff is way too cheap not to use it.
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