Anther good question Joe!
Before, during and after WWII, America was vastly working with many chemical compounds involving plastics, as we all know..
They had be strong enough, light enough, durable and inexpensive enough to make anything out of it! Think about plastics now....from your shower curtain, to plastic parts that hold an 800 Horse Power, full blown, jet fuel injected top Fuel Dragster together!!
I think when Delrin came around in the 80's for pocket knives, that was the mostly widely used plastic in many forms..
Before that, who knows!! I know that some plastics like Celluliod that we used before Delrin was another widely used knife handle plastic...the color paterns, the pretty an unique designs were incredible! Talk about dangerous!! We had a special cement and cinderblock shed JUST for the laquer and Acetone for printing, and sheets after sheets of Celluliod! Pinks, purples, yellows and greens! Pretty but deadly... this stuff was not only
Flamable back then, it was Combustible!! Drilling and sanding operations were always accompanied buy a bucket of water close by...we blanked a lot of this stuff in secondard blanking operation sections of the plant....tools had to be cooled in between
Just Bobby's opinion..Colonial Historian? Maybe....
