On one set of bumpers I removed a thin layer of cheap paint using carby cleaner and a rag (and maybe petrol and paint stripper at times). I got them back to bare plastic which is what I wanted, but was told the chemicals would not be good if I ever wanted to paint the same bumpers in the future.

I have now got some other stock bumpers and need to remove a few layers of paint, and I will probably paint the bumpers again properly. How is the best way to remove all the paint. Getting them dry ice blasted was surgested to me, as it would leave the plastic "chemically neutral" to accept paint later.