Cool, I like it when information on a product is all in one place.
I do believe it does look streaky on some plastics too. Wasn't to bad on the smooth mirror body. Although, I think polishing black plastic mirrors makes them look better. Worked really well on the mount part of the mirror that is a different plastic. Not as uniform as spray painting them, but pretty good.
You can basically paint this stuff on. I put on every coat very wet. Made sure I had good coverage, added another light line of product to the applicator, then then did a final pass to make sure it was even and smooth looking.
If the plastic is very faded and you are trying return to black, apply like above and do not over work the applicator on the surface that you have already applied product to. Do not try try to rub or scrub or work the product into the surface.
You are basically trying to add layers of paint at this point. The solvent in the product will dissolve the previously applied layers. So to remove as little as possible while applying another layer, quickly apply the product wet and smooth it out. Don't keep wiping. Just make sure you catch any runs, and if you start removing previous coats, stop. Wait 10-15mins, and try again.
I also discovered you can make it look ok on gray plastic by immediately wiping it with a dry side of the applicator. Basically removing most of the product and it may still not look perfect.
Here is my bumper retest. Different year car than my previous try, but the same results.
Gray rear bumper, black protector on top. Left, one coat plus what accidentally got on the other side of the tape line, tape line untreated, 3 coats on the black top piece, and one coat immediately dry wiped on the surrounding area.
Right was done with just one wavy wipe to show the streaky look on gray plastic.
This is what happens if you start or stop in an obvious place on gray or faded plastic.
Three coats on the wiper cowl. Lightly textured and a little streaky.
Mirrors 3 coats on the body, maybe 6 on the mount.
Door handle. Looked really good.
And my extremely faded mud guard. Did three coats and pulled the tape, then decided to do some more.
Three coats
Didn't keep count, but somewhere around ten coats
Did a section of the roof rails and cross bars too, but did not take pictures yet.
Also, it's a good idea to tape off the surrounding area to prevent staining. A damp rag will work to remove staining if you just applied it, and alcohol will remove it once it has dried.