early 20th century single stamped or wrought brass antique american rectangular-shaped "science" door or header plaque possibly fabricated by the commonwealth art metal company, boston, mass. two signs (the other reads: "laboratory") were salvaged from a new york city public school building. the flush mount sign retains the original baked-on black enamleled background. the slightly raised lettering is very clear and legible. no major wear evident. the nicely aged surface patina has not been cleaned or altered in anyway. the two opposed screw holes are for mounting purposes.