A1.2 Significance
A1.2.1 The processing of poly(vinyl chloride) (PVC) compounds
has greater influence on impact retention and some
influence on color retention. For this reason samples prepared
for weathering must be processed in a manner similar to the
commercial product while still permitting the use of laboratory
scale equipment. Color hold guidelines are represented by
ellipsoids or as an alternative, mathematical equations, both of
which allow determination whether the product meets the
performance criteria. The ellipsoids also allow determination
of the direction of color change and, therefore, are useful in
analyzing the weathering data.