From: jeroen@nospam.please   
      
   While playing with polarizing filters, I found a plastic ruler   
   that turns out to rotate the polarization angle of the light   
   passing through it by almost exactly 90 degrees. The ruler is   
   of a 1mm thick colourless plastic, rather flexible, clearly   
   not the usual polyethylene or polystyrene. It does not itself   
   polarize light, it just rotates it. The angle of rotation does   
   not seem to depend on wavelength. It's made in China.   
      
   What plastic could this be?   
      
   Thanks,   
   Jeroen Belleman   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)