Plastic heating

Has anyone ever used the method of heating up the plastics with a MAPP torch to give em a new look? I have some spare pieces i messed with the other day and was lookin for some advice. After a few tries I got some decent results by putting a good amount of heat on it for a very short time. Got alot of the scratches out or reduced the size alot. Only thing is its got a dull finish, not as shiny as what I have on the quad. Just wondering if anyone out there knows the trick.