SHORT-TERM TESTING OF WEATHERING RESISTANCE OF PMMA BY VARIOUS TEST INSTRUMENTS.

With the increasing amount of equipment available for short-term determinations of weathering resistance and the increasing effectiveness of such equipment, the question arises as to the comparability of the results obtained with older and with more modern instruments, especially since the reduction in the test period found in modern instruments is coupled with an increased UV content of the radiation. In many cases however, more importance is attached to agreement of results obtained with older and with modern instruments, than a greater reduction in test time. Tests show that the results obtained with a more efficient instrument with a higher proportion of UV rays are in good agreement with the results obtained with older instruments if, by using a special filter, the radiation spectrum becomes comparable. For figures see German text.