In the past, advertisements had to be durable and bold, able to catch the attention of passers-by and maintain their appearance over time.
Metal industrial advertising signs and enamel signs became popular due to their longevity.
There are couple types of signs. Tin lithograph signs are most common and can be found with embossed lettering and images or flat. Another type of Advertising sign is the Porcelain Enamel signs. Porcelain signs are much heavier than their counterparts.
Patina is important when determining the age and authenticity of an advertising signs. Patina is a thin layer that variously forms on the surface of copper, brass, bronze and similar metals, certain stones and wooden furniture (sheen produced by age, wear, and polishing), Or any similar acquired change of a surface through age and exposure. Patina can be “faked” on metal signs using chemical processes and exposure to the elements to speed up the aging process resulting in a rusty surface.
Authentic antique or vintage metal signs will have some signs of age through surface wear and, probably, some rust. Authentic rust that is a result of exposure to the elements over time will have a deep red color. Faux patina will have a bright red rust color or may even be printed on the surface. Little to no signs of age (wear) can also be an indicator that the sign is a modern reproduction.