How to Paint plastic bumper

[divinity]

Just want to run this with the pros and to check my steps...

Sanded bumper w/ 80grit
Primer bumper
Wet sand 400grit
Paint and clear.

How long min and max after the 400 grit wet sand must I apply paint?

For a beginner, if I have a small corner of fender that had body work done to (size about 4x6), should I repaint the complete fender? or try to blend it in?

If a small area on hood 12x12, fender 4x6, and the complete bumper, needs to be painted, is it just better to mask and paint complete front end? rather than do small spots and bumper?

[Len]

Is the bumper new or does it have damage? 80 grit is too coarse for most general sanding unless you're trying to remove filler or paint from the surface. After priming with a 2K filler primer then sanding it usually doesn't require that the color be sprayed within

As far as the painting goes we would usually spray the damaged areas then blend the color and clear the entire panel. On a job like yours we would probably spray color over the areas that need it then blend out the color and clear the entire front end. However this process could be different depending on the location of the painting so post pictures if possible and I (or someone else) may have some different advice.

[divinity]

bumper is OEM on car. I had some big scratches, so I used 80grit to get them out...

OOOpps then. I sanded the whole bumper w/ 80grit.

[Len]

I would use some 180/220 grit to remove the 80 scratches before applying a flexible filler primer then guide coat and sand with 400/600 before painting.

[divinity]

What would be the better way to do this if I needed to remove paint.

1. 80grit down to plastic
2. 220 to smooth out
3. primer filler
4. 400 wet sand w/ guidecoat
5. ready for base coat

?

[Len]

What would be the better way to do this if I needed to remove paint.

1. 80grit down to plastic
2. 220 to smooth out
3. primer filler
4. 400 wet sand w/ guidecoat
5. ready for base coat

?

If I were doing that job here I would remove the paint using a chemical stripper especially engineered for plastics then I'd clean and scuff the plastic using a red scuff pad. I'd clean the surface again with a good grease and wax remover and apply an adhesion promoter then apply my flexed filler primer if necessary then proceed to your steps 4 and 5.

[bump&grind]

If I were doing that job here I would remove the paint using a chemical stripper especially engineered for plastics then I'd clean and scuff the plastic using a red scuff pad. I'd clean the surface again with a good grease and wax remover and apply an adhesion promoter then apply my flexed filler primer if necessary then proceed to your steps 4 and 5.
that's what i would do too,especially the adhesion promoter if the bumper is made of tpo or polypropylene.adhesion promoter should also be applied before fillers on these plastics.but i think i would skip using wax and grease remover on the bare plastic.

[Len]

i think i would skip using wax and grease remover on the bare plastic.

Why wouldn't you use grease and wax remover on plastic? Have you ever painted plastic?