Don,
My understanding is, Paul-Son started with clay composition chips in the 70's.
When I spoke to Paul Indy 2 years ago, he declined to give me the make up of their chips. I believe them to now be a clay/plastic composition but they are still compression molded and not injection molded.
I guess I meant to say Paul-Son and TR King are the only 2 companies to still use compression molds.
Next time I talk to Dennis at TRK, I will ask about the make up of their chips.