Porcelain signs today are extremely popular and valuable for the great colors, designs, brands, and nostalgia that they bring out in the people who own and love them. I get the question a lot though – What is porcelain enamel and why is it so strong, durable, and beautiful?
To make the porcelain signs on the site manufacturers would take a heavy sheet of metal and start with a base coat of glass beads or powder that gets baked onto the metal at around 800°C which fuses the glass to the metal. Once the base coat is down subsequent layers of color are added one at a time to create the final design. This process is time and labor intensive which makes it very expensive but creates a very strong, durable, and high quality finish that was very popular as advertising in from the 1890s up until the 40s and 50s when the cost began to be too much for most companies who began using mass produced signs in metal or plastic.
The technique of layering on different colors one over another produces an effect on porcelain signs called shelving. When you look at a porcelain sign from an angle you can see visible ridges along the edges of color where one has been layered over another. You can also observe the layering where chips have damaged the porcelain and you can see the layering where a top layer has come off the top of a lower layer.
The technique of producing porcelain enamel signs provides a finish that is durable to weather and most things that could be a problem with signs that were painted on wood such as fading, rotting, peeling, etc. However, being made of ceramic makes the porcelain finish vulnerable to damage from rocks or other blunt impacts because of the brittle nature of the glass coating.