Plastic used in grading holders
Is there a logic to the plastics that PCGS, NGC, Anacs and ICG have been using? NGC seems to be a softer almost rubbery plastic, is that so it doesn't scratch so easily? Anacs plastic seems to be the hardest and ICG plastic seems to scratch the easiest, not sure on the old ICG holder vs. the current one.
How would you assess the quality of the plastics used? Maybe someone who knows the science behind them could comment.