Plain porcelain shaving mugs are quite common today (after all, every man had one) and aren't particularly interesting. However, there is one, less common type of shaving mug that is quite interesting and offers a glimpse into the life of a tradesman in the 19th century.
The discovery of Germ Theory by Louis Pasteur in the 1860s led to the creation of sanitation laws that required a barber's clients to have their own shaving mugs which could not be shared with other patrons. Blank shaving mugs were imported from France and Germany and personalized by painting the man's name in elegant, fraktur calligraphy. Sometimes a scene was also painted on the mug which depicted the man's profession or trade. These occupational shaving mugs were displayed in the barber shop and served as a type of advertising. When someone went looking for a painter, carpenter or lawyer, they could stop by the barbershop and check out the shaving mugs to find the professional they needed.