original and hard to find early porcelain enameled american factory "positively no smoking" factory sign fabricated by the burdick sign company, chicago, ills. the early vitreous enameled sign contains slightly sunken white lettering. the richly colored dark cobalt blue is indicative of turn of the century sign making using porcelain enamel. the heavy gauge steel sign is in good shape with sporadic surface wear evident. salvaged from an old tool & die factory located in hammond, ind. measures 18 x 24 inches.