polypropylene question.

O

OJ86

Promoted Users
I have this custom golf cart body, parts are polypropylene, I was just going to wash with dawn soap/water, scuff real good, adpro and seal and paint.. Or should I sand then 320, epoxy and then prep the epoxy for a more durable finish? The parts are brand new.



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OJ, Being it's PP I would normally follow plan #1. Dawn, then scuff, or scuff with scuff stuff, adpro, seal and paint. Even if you do it differently you are going to need to wash it and adpro it. If the panels look straight then no real need for epoxy or other primer. In this case longevity would mainly be determined by adhesion
 
Ok. Thanks guys. I remember a long time ago I did the flame treatment on some parts but I don't know if that did anything honestly.
 
I think JimC may have talked about flame treatment( I may be wrong) but the tech guys at SEM feel the flame treatment may not work that well and really not needed with there products.
 
I've found that some gray pads with Scuff Stuff can leave raised scratches, which causes extra work if the intent is to seal and shoot (it looks like these parts are great candidates for that). We have been using gold pads and Standox branded prep paste, which is finer. If I did not have the Standox prep paste, we would use gold pads and Dawn.

Oh, and we wash them VERY well with strong Dawn solution inside and out right off the bat. This helps prevent contaminant transfer from touching the backside when working. I guess a lot of this goes without saying to you, orange, but others will read this, too.
 
I found the same thing Crash. Sometimes 2 coats of sealer will do the trick with the scratches, sometimes not. In the event that you don't have gold pads, you can use grey if you don't scuff with a lot of pressure. Once I started doing that, no more scratches, or at least no more deep scratches. TPO seems to scratch easier than PP IIRC. Light pressure you should be OK.
 
Wouldn't the relatively short time of using epoxy be worth the time? It's just extra insurance.
 
AAE said:
Wouldn't the relatively short time of using epoxy be worth the time? It's just extra insurance.
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Often I will do a kind of hybrid technique with stuff like this, shooting 1.5 coats of epoxy thinned to about 25% the night before, then the next morning, lightly scuffing with sanding sponges to remove any texture or trash, and go right to base coat.

I don't think there is a lot of difference with these kinds of parts between 3 coats of epoxy and 1.5 coats of epoxy sealer, they don't need it for corrosion protection, and given the nature of the material I don't believe it helps with chip resistance. Happy to be contradicted, though, I've never really done a study, other than we don't have comebacks!
 
crashtech said:
Often I will do a kind of hybrid technique with stuff like this, shooting 1.5 coats of epoxy thinned to about 25% the night before, then the next morning, lightly scuffing with sanding sponges to remove any texture or trash, and go right to base coat.

I don't think there is a lot of difference with these kinds of parts between 3 coats of epoxy and 1.5 coats of epoxy sealer, they don't need it for corrosion protection, and given the nature of the material I don't believe it helps with chip resistance. Happy to be contradicted, though, I've never really done a study, other than we don't have comebacks!
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I'm not very smart, but, it seems that a plastic that needs ADPRO,would benefit from an epoxy sealer or even a full coat. I'm reluctant to mention a non SPI product, but I have heard good things about Polyvances Bumper and cladding primer. Apparently, there's not scuffing required. But, you can't use an activated base with it.
 
AAE said:
I'm not very smart, but, it seems that a plastic that needs ADPRO,would benefit from an epoxy sealer or even a full coat. I'm reluctant to mention a non SPI product, but I have heard good things about Polyvances Bumper and cladding primer. Apparently, there's not scuffing required. But, you can't use an activated base with it.
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Just to be perfectly clear, I don't think anyone is saying to go straight to paint after adpro. We are saying to use epoxy sealer.
 
pp usually gets fuzzy when you sand it. i can tell you for certain that flame treating is hands down the best thing you can do for adhesion. its literally night and day difference than using adpro by itself and only takes a few seconds to do. i have dirt bike plastics that i have done on my own bike and a year and a half later i cant get the paint off if i tried. those got flame treated, adpro and 2-3 coats of epoxy on them. left them in a matte black. those really take some serious abuse also.
 
Thank you for all the replies. I think I have process I am going to do now. I washed the parts last night and I noticed alot of mold marks that Ill level out and epoxy.

Jim, do you flame treat and then wipe off with alcohol?
 
yes, propane torch and just quickly run the tip of the flame over the plastic. go back and forth until you hit the whole surface. just the flame tip should contact the plastic. the object isnt to heat the plastic up. the flame tip just stress relieves the plastic surface so it will accept paint. move the torch quickly. maybe 24" per second. you should barely be warming the part
 
no, i generally get the part all clean and ready for paint first then ill flame it, tack it off, adpro, epoxy.......
 
Oh, ok so you do it right before you paint. Ive seen some where they flame torch it, wipe it down with alcohol to get any type of mold release out and then rescuff and move on with the adpro and epoxy.

I will try your method...These are bigger parts, do you think there is a time frame I should ne concerned with?
 
Yes that method is completely wrong. The flame treatment only lasts about 30 minutes and if you scuff afterwards you have destroyed what you did with the flame.
 
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