Hello and welcome to Doll News Monthly.
So over the years minor changes have been made to the mixtures of Silicone.
Maybe different pigment systems to improve the color and matting agents to help reduce shine that is often a byproduct from silicone .
I would say the largest change to silicone based dolls was over two decades ago when Platinum based silicones took the place of Tin Cured silicone.
