REFRACTIVE INDEX for any substance is the ratio of the volocity of light in a vacuum to its
velocity in the substance. It is also the ratio of the sine of the angle of incidence to the
sine of the angle of refraction ASTM D642.


Fluorcarbon (FEP)	                  1.34 -
Polytetrafluoro--Ethylene (TFE)	          1.35
Chlorotrifiuoro--Ethylene (CTFE)	  1.42 -
Cellulose Propionate	                  1.46 -
Cellulose Acetate Butyrate	          1.46 - 1.49
Cellulose Acetate	                  1.46 - 1.50
Methylpentene Polymer 	                  1.485 -
Ethyl Cellulose	                          1.47 -
Acetal Homopolymer	                  1.48 -
Acrylics	                          1.49 -
Cellulose Nitrate	                  1.49 - 1.51
Polypropylene (Unmodified)	          1.49 -
Polyallomer	                          1.492 -
Polybutylene	                          1.50 -
Ionomers	                          1.51 -
Polyethylene (Low Density)	          1.51
Nylons (PA) Type II	                  1.52 -
Acrylics Multipolymer	                  1.52 -
Polyethylene (Medium Density)	          1.52. -
Styrene Butadiene Thermoplastic 	  1.52 - 1.55
PVC (Rigid)	                          1.52. - 1.55
Nylons (Polyamide) Type 6/6	          1.53 -
Urea Formaldehyde	                  1.54 - 1.58
Polyethylene (High Density)	          1.54 -
Styrene Acrylonitrile Copolymer 	  1 .56 - 1.57
Polystyrene (Heat & Chemical)	          1.57- 1.60
Polycarbornate (Unfilled)	          1.586 -
Polystyrene (General Purpose)	          1.59
Polysulfone	                          1 .633