Painting over plastic parts

1073 Views 4 Replies 4 Participants Last post by jcclark, May 11, 2022

farmansyed08

Discussion Starter · May 11, 2022

Hello everyone,

I have a 2004 Lexus GS300 that I am looking to do a paint job on. I'm new to doing full car paint jobs for sure, but I've done a lot of research and with the help of some amazing people on this site I think I've got my process for car prep down. Here it is:

1. Start block sanding with 180 grit.

2. Then move to 240 grit.

3. Then move to 320 grit.

4. Then move to 400 grit wet sand.

5. wash the car, remove all oils, solvents etc. After this apply primer that will stick to bare metal.

6. now apply basecoat.

Question is, I assume the process is a little different for plastic parts. My car still has all the factory paint on it, just awful clear coat damage. Would I be fine just scuffing the plastic parts with 800 then 1000 grit, so I am creating a good surface for the next coat to adhere to?

And if so - after scuffing would I apply primer first and then basecoat, just like the metal parts? Or basecoat directly?

For reference, here is the urethane primer I will be using - Kirker Black Diamond Low VOC Urethane Primer 2K Gray.

Kirker Black Diamond Low-VOC Urethane Primer (2K) - Gray, Gal

High-Build Primer/Sealer! Versatile urethane 2K primer can be mixed as a high-build primer or thinned more to be sprayed as a urethane primer sealer with exceptional hold-out. Delivers maximum build with excellent filling capabilities and superior sandability (wet or dry). Creates a super...

www.tptools.com

Thank you!

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Ford blue blood

· #2 · May 11, 2022

You need to move the "wash" part to the first step. Wash and rinse with Dawn. Then wipe down the entire car with "wax and grease remover". Sanding before washing will result in "stuff" getting embedded in the surface.

Unless you have deep scratches and damage to the metal there is no need to go with that many steps. Hit it with 180 to remove the old clear. Come back with 400, then prime. Block again with 400. Spot any break through, apply a sealer and shoot the base followed by the clear.

The process is pretty much the same for the plastic/rubber parts but with a "flex" additive added to the paint. Get a hold of an automotive paint supplier. He/she can give the best advice with respect to materials. One rule I have found applies for the best finish is use the same manufacturer for all the products from start to finish.

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ogre

· #3 · May 11, 2022

i'm not an expert, unless the vehicle has never been outside
i'll add 2a: fill dents and stone chips. 2b prime. 2c block sand with 240, repeat #2, repeat #2
i don't see a need to wet sand primer ever unless it's a $50k paint job

plastic/flexible parts have their own primer and paint

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farmansyed08

Discussion Starter · #4 · May 11, 2022

Sounds good, thank you so much for the insights I really appreciate it. I have gotten in touch with Kirker to see if they have any options for plastic parts. As Ford blue blood said it would be really nice to be able to get everything from one supplier. Will update with what I find out!

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jcclark

· #5 · May 11, 2022

I see no need to go past 240 if you're putting primer over it, primer will fill
the scratches no problem. I stop at 180 sometimes and don't have a problem.
The real key is to let your primer fully cure before sanding it.
I like 48 hrs, it rally reduces shrinkage a lot compared to just 24 hrs.

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Kirker Black Diamond Low-VOC Urethane Primer (2K) - Gray, Gal

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