Because without plasticizer additives, most plastics get brittle and crack after a while. The raw plastic is stiffer, less flexible, and slightly porous unless

Because without plasticizer additives, most plastics get brittle and crack after a while. The raw plastic is stiffer, less flexible, and slightly porous unless a buttery filler is added, but it can slowly ooze out and get sticky. Armor All and silicone are a similar aftermarket replacement that soaks in and acts similar to the original plasticizer. https://en.wikipedia.org/wiki/Plasticizer https://en.wikipedia.org/wiki/Plasticizer