Prince of Space wrote:
Getting back to the original question, how many Golden Age heroes had full masks? The only ones I can think of (without research) is the Atom, Doctor Fate and Sandman, and the latter two also sported half-masks at various times. (Hawkman almost qualifies, but his chin wasn't covered.) Batman's mask is the rule rather than the exception.
The Atom switched to a half mask towards the end of his GA adventures and wore it until the 90s.