The old saying “Necessity is the Mother of Invention” is particularity applicable to the use of synthetic rubbers in molded products. In the conversion to these materials the manufacturer has been constantly confronted with the necessity of changing from one synthetic rubber to another. At the same time it was necessary to maintain quality standards along with factory production. Sometimes the results obtained have been far more than anticipated. Before the conversion program on gas mask parts it would have been hard to believe that it would be possible to produce these parts from Neoprene GN (GR-M) compounds in the same or shorter curing cycles than used on rubber compounds. However, this has been accomplished. Many other molded products have been converted from natural rubber to synthetic rubbers, although numerous problems have been encountered in the change-over. Some of these problems and the methods by which they were solved may be of interest to those who make and use rubber products.