Sanding Plastic

[tgfhatch]

Wasn't sure where to put this so the break room looked tempting. I'm trying to get some interior pieces smooth. Note that they are plastic!

Can anybody recommend a good way to get the plastic smooth? So far I've gone over it with 220 up to 600 gritt sand paper, and it has put a dent on it and thats about it. Doesnt seem to be getting smooth!

Also does anybody know any good products that will remove paint from plastic?

Thanks!

[LiquidBlack]

You'll need to move onto finer grits, such as 800 all the way up to 1500 to 2000 to get it completely smooth, I'd imagine.

Out of curiousity, what are you sanding?

[tgfhatch]

door panels...

[Shiny Lil Detlr]

Have you been dry or wet sanding? What I would recommend is to go from your 600-grit dry, up to 800 dry for another pass. Hit it with some 1,000 wet after that, and dry/clean everything off with rubbing alcohol. Then put a few coats of sandable primer on the parts. Once that dries (~30 minutes) come back and wetsand the primer with 1500 and 2000 grit. Clean everything up again and you can base/clear the parts. Once the clear has had enough cure time, you can wetsand with 2500 or 3000 grit and compound/polish it to make everything nice and uniform.

As far as removing paint from plastic, I'd try acetone first. If you're just re-painting it though, I'd go ahead and just sand it off with some 1,000 grit, and lay new primer down.

[tgfhatch]

wow thanks shiney!!

I've currently been dry sanding. However, the paper I have is for wet / dry. Would you Shiney (Hopefully, you check back to this forum) go about that with a palm sander or by hand?? I've been doing a little bit of both! I'm having the hardest time getting the initial roofness down smooth!

but I will try it out!!

dumb question coming.. does sand paper get smoothier or roofer as it moves up in size?

thanks shiney again for the help!

[gb387]

Originally posted by tgfhatch
dumb question coming.. does sand paper get smoothier or roofer as it moves up in size?

The higher the number the finer the paper is, using your term, "smoother"...

[Mike Phillips]

Just to note, some materials don't lend themselves to abrading, polishing, or becoming smooth...

Best of luck with this...

[tgfhatch]

mike, is that a hint to give up on the project of trying to get them smooth??? sure sounds like it to me!

[Shiny Lil Detlr]

Originally posted by tgfhatch
mike, is that a hint to give up on the project of trying to get them smooth??? sure sounds like it to me!

No, all he's saying is that some parts arent as easy to make "perfectly" smooth as others. If you're dealing with "cushy" plastic (foam backed) you may have an issue; if it's hard (which I assume it is since you've already used 220 and 600 on it) you won't have a problem. I did the hard, textured plastic mirrors on my truck with no troubles to speak of.

Before


After


See? No big deal, you just have to be thorough.

[Shiny Lil Detlr]

Originally posted by tgfhatch
wow thanks shiney!!

I've currently been dry sanding. However, the paper I have is for wet / dry. Would you Shiney (Hopefully, you check back to this forum) go about that with a palm sander or by hand?? I've been doing a little bit of both! I'm having the hardest time getting the initial roofness down smooth!

but I will try it out!!

dumb question coming.. does sand paper get smoothier or roofer as it moves up in size?

thanks shiney again for the help!

I personally think it's easier to control it by hand with a hard-foam backing pad. You can get better results in contoured areas, and you will know exactly how much plastic you're removing (remember, you ARE removing material, making the piece you're working on thinner than it originally was). Remember that Rule #1 of this type of project is PATIENCE to complete the Prep Work the right way, before rushing into paint.

You have to realize that with the larger grit sizes you use, especially on hard plastic, you're going from the texture molded into the part, to the scratches/gouges texture left by the sandpaper. The higher you go in "grit numbering," the smaller those particles get. Once you've reached a high enough number, they'll have all been smoothed out. It's important to go through it gradually up to higher numbered papers. It's kinda the same principle as "Diminishing abrasives" in the Meguiar's polishes. Each higher number removes the texture left behind by smaller ones, etc.

So, remember, PATIENCE and PREP are your keys to success on this. Good luck!

[aaron33]

Is it a SMART car panel? I fixed a graze on my friend's SMART. Went from 800, 1200, 2000 all wet. After that, it was still matte and hazy so I went on to Autosol. Worked it in and the finish was now smooth and shinier. After repeating 2x I then went on to paint swirl removers and treating it like a clear coated paint.

[Mikeyc]

If the panel is textured and you're trying to get it smooth and paint it maybe you should mix up some bond-o spread it over the textured area and then sand. This way you won't thin the plastic and bond-o is much easier to sand. In the end you're painting over it so the bond-o will be invisible.