Flamethrowing the outer black moulding/trim

Plastic pigments outgas or whatever and float away.

One thing I've seen done is using a flamethrower to bring out the lower pigments:
https://www.youtube.com/watch?v=NjDbttpJ3GY

I had some extra trim pieces laying around and thought I'd give it a shot. It appears there's a layer on top of the plastic that tends to peal. Possibly sanding, flaming, and applying lacquer could be the move.

Here are my results on the temporary pieces:

https://i.postimg.cc/hzSk4mj5/IMG-2368.jpg

https://i.postimg.cc/DWdVK62G/IMG-2369.jpg

I've heard of doing this with a heat gun but never tried it. Supposedly works a time or two, then you run out of the plastic "oils."