The 1981 exhibition held in Marburg Castle to honor the 750th anniversary of St. Elizabeth's death included a number of very valuable artifacts such as old manuscripts and books. The rooms were kept dark, lit only by low ultraviolet daylight lamps. It was explained to visitors that manuscripts, prints, and fabrics should not be exposed to daylight for any extended period of time. A number of organic substances are known to absorb UV radiation. It is possible to produce colorless panels of Plexiglas containing enough UV absorber to filter out the unwanted UV component of daylight and still transparent enough for exhibition use. A graph illustrates the light permeability of Plexiglas GS201 panes as compared to that of silicate glass panes of roughly the same thickness, showing that the Plexiglas panes completely filter out the high energy UV range between 320 and 380 nm, responsible for hydrogen peroxide formation. Thus, light sensitive objects that must share exhibition space with non-light sensitive objects can be shown in daylight in cases made of Plexiglas GS233 and GS201. -- AATA