Nope, it's not a better way to tell what month it is. You'd have to spell better for that.
A supercalender is a series of rolls, alternating between steel or cast-iron rolls and fiber-covered rolls, used to press various kinds of paper into thinner, glossier forms, in a process known as supercalendering.
One of the better-known types of paper made using a supercalender is glassine.