Prepping Plastic for Paint

[DoubleDingo]

I recently ordered a new cowl for my 1991 Jeep Cherokee, so a Chrysler squarebody...lol... It appears to be plain plastic, it's black. What should I do to prep it for paint? My old one warped in the summer sun, and I was able to find a new one from Mopar. The new one was actually the same price as sourcing a used or Repop one from Dead Jeep.

 

[rwjtexas]

There is a ton of information on this web page to search basically you clean it a zillion times, use the correct degreasser and correct activatior and paint in multiple coats starting light to medium light then a semi heavy flowing coat over the entire piece. best if you can hang in in a clean envirornemtn without any wind. I painted all of my plastic on a painters rack I bouth but I did every piece of my Blazer, plastic and vinyl.

EDIT: USE Cheap Throwaway vinyl / nitrile Gloves to keep body oils off of plastic when handling and wiping down with the degreasser as well as painting.

I used SEM products - SEM Soap with Grey Scotch Pads to clean, SEM Solve for degreaser, on plastic you have to select the correct activator ... one for ABS and one for Olfins (and everything else)... to determine which plastic you have take a tiny bit of acetone and place on a hidden piece of the plastic, if it does NOTHING ... it is Olfins ... if it starts to "Melt" it is ABS. Knowing the type of plastic will allow for the correct activator. Each requires a different approach to apply the first light coat of the desired color. pult light coats on first then follow up with heavier coats followed up by a nice flowing coat.

 

[DoubleDingo]

There is a ton of information on this web page to search basically you clean it a zillion times, use the correct degreasser and correct activatior and paint in multiple coats starting light to medium light then a semi heavy flowing coat over the entire piece. best if you can hang in in a clean envirornemtn without any wind. I painted all of my plastic on a painters rack I bouth but I did every piece of my Blazer, plastic and vinyl.

EDIT: USE Cheap Throwaway vinyl / nitrile Gloves to keep body oils off of plastic when handling and wiping down with the degreasser as well as painting.

I used SEM products - SEM Soap with Grey Scotch Pads to clean, SEM Solve for degreaser, on plastic you have to select the correct activator ... one for ABS and one for Olfins (and everything else)... to determine which plastic you have take a tiny bit of acetone and place on a hidden piece of the plastic, if it does NOTHING ... it is Olfins ... if it starts to "Melt" it is ABS. Knowing the type of plastic will allow for the correct activator. Each requires a different approach to apply the first light coat of the desired color. pult light coats on first then follow up with heavier coats followed up by a nice flowing coat.

Thank you for that detailed response. Now to find where I can source SEM products

 

[bucket]

You mean the exterior cowl panel, between the hood and windshield?

If so, check to make sure it doesn't have a primer on it that wipes off with lacquer thinner. If it passes that test, simply scuff it and shoot it with automotive paint.

 

[DoubleDingo]

It looks to be bare plastic.

 

[bucket]

It looks to be bare plastic.

Typically a red scotch brite pad will work fine for paint prep.

 

[DoubleDingo]

This is the culprit

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[bucket]

I'm surprised those are still available. But yeah, scuff it and shoot it. Be sure scuff real good down into the nooks and crannies so the paint doesn't start chipping off after a couple years.

 

[DoubleDingo]

I was surprised too. Glad I checked mopar before buying a used or repop.

 

[brooksman9]

SEM products you can get from Summit or a local automotive paint store. They also make an adhesion promoter for painting plastic parts as well but I do not know if SEM makes on.

 

[bucket]

Painting rigid exterior plastic parts is not nearly as finicky as softer plastic parts like bumper covers or interior panels. Pieces like this cowl panel really don't require any kind of special prep or products.

 

[rwjtexas]

SEM products you can get from Summit or a local automotive paint store. They also make an adhesion promoter for painting plastic parts as well but I do not know if SEM makes on.

Yes SEM makes both types of plastic Activators (ABS and Olfins) as well as Vinyl Activator for Dash pads, arm rests etc. I used all three in the restoration of my blazer

Also once you know what SEM Products you may want .. I bought most of mine off Amazon except for the top coat which I got a local Auto Paint supply house and USA 1

 

[CalSgt]

Painting rigid exterior plastic parts is not nearly as finicky as softer plastic parts like bumper covers or interior panels. Pieces like this cowl panel really don't require any kind of special prep or products.

This has been my experience ^^^

I’m always a fan of epoxy sealer on just about everything since it seems to adhere well to so many substrates and subsequent coats (color etc.) stick to it good too

 

[dhartman]

There is a ton of information on this web page to search basically you clean it a zillion times, use the correct degreasser and correct activatior and paint in multiple coats starting light to medium light then a semi heavy flowing coat over the entire piece. best if you can hang in in a clean envirornemtn without any wind. I painted all of my plastic on a painters rack I bouth but I did every piece of my Blazer, plastic and vinyl.

EDIT: USE Cheap Throwaway vinyl / nitrile Gloves to keep body oils off of plastic when handling and wiping down with the degreasser as well as painting.

I used SEM products - SEM Soap with Grey Scotch Pads to clean, SEM Solve for degreaser, on plastic you have to select the correct activator ... one for ABS and one for Olfins (and everything else)... to determine which plastic you have take a tiny bit of acetone and place on a hidden piece of the plastic, if it does NOTHING ... it is Olfins ... if it starts to "Melt" it is ABS. Knowing the type of plastic will allow for the correct activator. Each requires a different approach to apply the first light coat of the desired color. pult light coats on first then follow up with heavier coats followed up by a nice flowing coat.

I recently ordered a new cowl for my 1991 Jeep Cherokee, so a Chrysler squarebody...lol... It appears to be plain plastic, it's black. What should I do to prep it for paint? My old one warped in the summer sun, and I was able to find a new one from Mopar. The new one was actually the same price as sourcing a used or Repop one from Dead Jeep.

I can help with this one, I quick call to one of your local body shops should give you a great location to where to pick up some supplies locally vs ordering online however both are great options.

Yes a red scotch bright pad is perfect for scuffing up the surface, next step is was it with dawn dish soap. There is a oil that is on or in the plastic that will and or can give you a fish eye effect.

It is also recommend to use adhesion promoter. Then apply a primer while the adhesion promoter is tacky. Once the primer is Dry hit it with another quick scuff with a gray sotoch bright pad then apply you paint/clear

 

[DoubleDingo]

Thank you everyone for the great replies. This cowl will look better than the rest of jeep when I am finished with it