Parylene exhibits very little absorption in the visible region and is, therefore, transparent and colorless. Below about 280 mu both N and C absorb strongly.

Ultraviolet Spectra of Parylene C and N

Both parylenes are relatively featureless to at least 50 micron wavelengths (except for a few characteristic peaks), especially in thin film form (<1 u).

Radiation and Weathering Resistance

Parylene C and N films show a high degree of resistance to degradation by gamma rays in vacuum. Tensile and electrical properties were unchanged after 100 megarad dosage at a rate of 1.6 megarads per hour. Exposure in air leads to rapid embrittlement.

Although stable indoors, the parylenes are not recommended for use outdoors when exposed to direct sunlight.