I discussed Metrolite, Deccalite, Merco Plastic, and Sav-o-flex! All were branded PVC, Styrene and other plastics used to replace shellac. If you can't recall the details go here. Vinylite was the Bakelite brand name for transparent vinyl plastic. Vinylite was Vinyl chloride (CH2=CHCl) a plastic made through a reaction between ethylene, oxygen, hydrogen chloride and a copper catalyst.
By the 1950s in America there were already long-playing 78s. these were 12-inch platters instead of the normal 10-inch and they had narrower grooves. These more compact grooves allowed for more grooves in the blank. Of course the idea of long-playing at the time was 7 minutes. As in everything consumers sought a better product, longer playing time, higher fidelity, more durability... In 1930 the Union Carbide Corporation debuted the polymer Vinylite™ . It was a copolymer of vinyl chloride and vinyl acetate.
As a result groove width was further reduced. They found through testing that speed could be reduced by more than half. (78 ÷ 2 = 39rpm) These were called microgrooves and they made for abotu 16 minutes of playtime. They also reduced surface noise, less breakage... A radical improvement. But it was softer, much softer. Overtime in storage it scuffed and gaps could form between grooves allowing bleed. early Vinylite also discolored dover time. The red Vinylite turned black and more opaque. the black Vinylite became dark gray.
Over time the term vinylite came to mean colored vinyl and our more common black vinlite was just called vinyl. In Euopre and Russia red vinylite was faily common place possibly causing the shift. And in the U.S. the Session record label released red 12-inch releases on Vinylite. Session made the switch for audiophile not aesthetic reasons. If anything vinylite was more expensive than shellac even in times of scarcity even accounting for breakage. They continued to flirt with shellac they reduced their pressing costs, as with other jazz labels got a negative reaction as retail.