1. Scope1.1 This practice covers the basic principles and operatingprocedures for using fluorescent UV light, and water apparatusintended to reproduce the weathering effects that occur whenmaterials are exposed to sunlight (either direct or throughwindow glass) and moisture as rain or dew in actual usage.This practice is limited to the procedures for obtaining,measuring, and controlling conditions of exposure. A numberof exposure procedures are listed in an appendix; however, thispractice does not specify the exposure conditions best suitedfor the material to be tested.