Prepping Plastic for Paint

[Snoots]

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

Amazon, Eastwood or NAPA. Choose your poison.

 

[Jeff Lewis]

Scotch brite, bulldog adhesion promoter then paint.

 

[sodell33]

SEM is best.

 

[bucket]

Ok, now I'm really curious... why do people keep suggesting SEM products for painting an exterior part that needs to match the rest of the body? SEM products are primarily for interior plastics. The products they sell for exterior use are things like truck bumper paints and universal trim black. Don't get me wrong, I like SEM products and have used them a bunch, but how does it apply here?

 

[Scribbles]

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.

Great reply, I'm an audio guy and paint plastic all the time. The main part here in AZ is the degreaser. With our heat the plastic off gasses bad, so proper cleaning and cleaning and cleaning is a must.

 

[rwjtexas]

Ok, now I'm really curious... why do people keep suggesting SEM products for painting an exterior part that needs to match the rest of the body? SEM products are primarily for interior plastics. The products they sell for exterior use are things like truck bumper paints and universal trim black. Don't get me wrong, I like SEM products and have used them a bunch, but how does it apply here?

In my opinion he is painting an outside plastic piece ... same as the bumpers and trim ... it's just hard plastic and not soft plastic.

The main issue is cleanning, degreasing, and usingn the correct activator depending on the type of plastic, ABS or Olifens.

With Metal you have to clean and prime and topcoat. Same as you know for plastic.

The Key in my mind is the actifvator / primer. Use Duplicor exterior paint to match the body, but you have to prep the piece to accept using the correct adhesive / activator.

My thoughts ... I have used the SEM Plastic paint on items inside the engine compartment .. so far they have done very well.

The time I used standard primer on plastic and tried to topcoat without "opening up" the plastic the topcoat failed shortly after painting.

 

[DoubleDingo]

I do have the duplicolor paint. It's definitely the prep that I want to get right. The plastic isn't very hard, it has some give to it. Probably why the original one warped in the summer sun after years of being out there. But may not be as pliable as bumper plastic.

 

[bucket]

In my opinion he is painting an outside plastic piece ... same as the bumpers and trim ... it's just hard plastic and not soft plastic.

The main issue is cleanning, degreasing, and usingn the correct activator depending on the type of plastic, ABS or Olifens.

With Metal you have to clean and prime and topcoat. Same as you know for plastic.

The Key in my mind is the actifvator / primer. Use Duplicor exterior paint to match the body, but you have to prep the piece to accept using the correct adhesive / activator.

My thoughts ... I have used the SEM Plastic paint on items inside the engine compartment .. so far they have done very well.

The time I used standard primer on plastic and tried to topcoat without "opening up" the plastic the topcoat failed shortly after painting.

It's all in the products that you use and the specific type of plastic that the paint is being applied to. Mixing and matching products is where you run into issues. Often times A LOT of issues. Generally speaking, semi-rigid plastic products only need a scuff and a shoot basically, as long as they have some kind of primer sealer on them that is compatible with the solvents used in the top coats that will be applied. Mixing brands and types of materials and using them together is what causes problems. A good mechanical bond is all that's needed for rigid and semi-rigid plastics.

Also, most aerosol primers are crap and have absolutely no business being used on exterior bodywork. There are only a few that are acceptable to use on exterior bodywork.

 

[mxer147]

I’m deciding on restoring my interior plastic panels, I have read a lot on here and purchased the SEM coating solution, adhesion promoter and dye.

Is it really dye, and it changes the plastic to a different color or is it a coating that could scratch off and/or fade with UV rays? My truck stays outside so it will have to withstand Mother Nature’s abuse.

I painted the panels previously with Krylon Plastic Fusion blue paint which scratched off easily and faded quickly from UV, I wasn’t satisfied with those results. I would like to avoid that if SEM is similar.

I am also considering a partial vinyl wrap on the panels. Can anyone share their experience using a vinyl wrap on slippery interior plastic panels?

 

[Grit dog]

I’m deciding on restoring my interior plastic panels, I have read a lot on here and purchased the SEM coating solution, adhesion promoter and dye.

Is it really dye, and it changes the plastic to a different color or is it a coating that could scratch off and/or fade with UV rays? My truck stays outside so it will have to withstand Mother Nature’s abuse.

I painted the panels previously with Krylon Plastic Fusion blue paint which scratched off easily and faded quickly from UV, I wasn’t satisfied with those results. I would like to avoid that if SEM is similar.

I am also considering a partial vinyl wrap on the panels. Can anyone share their experience using a vinyl wrap on slippery interior plastic panels?

I like SEM “dye” so far.
IMO it is a “paint” not a dye. Same product to coat fabrics or hard plastic or even metal.
Can’t say how good the UV resistance is, but have had some small plastic and carpet pieces painted with it for a couple years now (bottom door cards carpet with plastic vents) and the stuff stays put where you spray it.
Recently did a few pieces of the interior trim in the 77 as a color test. Some plastic some metal, some bare metal.
I tried to scratch it off (finger nail) and it stayed put except on the bare metal.
FWIW

 

[bucket]

Right, SEM is a coating. I don't think they ever state it as a dye?

At any rate, I've UV tested to stuff for many years and it holds up fantastic. Adhesion is fine, the key is good prep and a solid base material. No chalky deteriorating plastic.

 

[Grit dog]

I only suggested their primer for plastic. Used single stage urethane over it and it’s made it 2 years in the Florida sun on a front spoiler that gets beat up by bugs curbs sun and road debris. Nothing has peeled. And impact chips don’t seem to be as a result of weak primer.

 

[bucket]

Honestly, I've never used their primer or even their prep stuff. I've always just washed with soap water, then a scuffing with a gray scuff pad and denatured alcohol. That's with interior stuff. Excellent results that last.