What is another name for the theater masking referred to as the act curtain?

Answer 1

The act curtain is also called the grand drape.

Answer 2

The Act curtain is the large curtain at the front of a proscenium stage that covers the stage entirely. We call it the act curtain because it is brought down at the end of an act as a convention for the audience to know that it is the intermission. It also allows the backstage crew to change the scenery out of view of the audience.

It can either open and close laterally via a pulley system, or it can be raised up by the fly system. Other names for it are the Grande Drape, orThe Main here in the US..

Answer 3

There are many other names for an act curtain. For modern theatre, it will be a scrim, backdrop, drop, etc.