I suspect you are experiencing the removal-difficulty of flashed/dried-up M105 from painted plastic panels...
moreso than painted metal panels...due to the plastic-substrate not being as good as a conductor of
the heat build-up from its paint being buffed/polished. Metal substrates tend to be just the opposite.
(I also suspect other manufacturers' compounds/polishes may similarly 'act-up' on occasion)
Other ways to possibly say this, as it refers to vehicle panels, is that:
At the macro-level...
-Since most metals are good thermal conductors, they warm up quite quickly and spreads (transfers)
the heat more rapidly throughout the entire metal-panel...not in one area, so to say.
At the micro-level...
-The
"heated-up paint" on the metal-panel (ex: from buffing), is transfered from the higher temperature paint
to the lower temperature metal substrate in the form of, what I'll call:
'molecular-kinetic energy'...
which causes a more evenly distributed heat transference throughout the bulk of the metal-panel.
Now...Although scientists have recently discovered/developed a technique for using plastic to
conduct electricity (by exposure to ion beams)...Most plastics will not transfer, or disperse,
heat at the same rate as metals---Causing more heat to remain on/in the paint and, therefore,
offering-up even more of an
"oven-effect"...for liquids so deposited thereon.
One more item that may be of interest:
Don’t forget that flex-additives may change the paint's chemistry/characteristics when "heated-up", also.
BTW:
One easy way I've found to remove dried-up product,
is to re-wet it with the same product---then try: Again.
Bob
