I'd like to add poly is essentially liquid plastic. (diybeautify.com)
I then made a silicon rubber mold and all the supports are cast with a 2 - part liquid plastic. (romanovgrave.com)
In 1903 Edouard Benedictus, a French scientist, dropped a glass flask that had been filled with a solution of cellulose nitrate, a sort of liquid plastic. (businessinsider.com)