Blue ghost signs

I don't often see blue ghost signs. But I saw these on 32nd Street in NYC this week.

According to a website called Ephemeral New York, "Doehler Metal Furniture owned the building these ads appear on, on 32nd Street. ...They seem to have had a lot of contracts with the Army during World War II. Manning-Bowman had a showroom on the seventh floor. The Connecticut-based electronics firm made things like waffle irons and coffee makers."