What Are Cobalt Blue Jars Used for?

Essential Oil

• Cobalt blue jars or bottles are used for storing essential oils. When used with a tight lid, cobalt blue bottles can help avoid evaporation and protect the essential oils from receiving sunlight, which causes deterioration within the oil. Protecting essential oils from sunlight and open air are the two main factors in keeping oils fresh during their shelf life. Some oils have a longer shelf life than others, so storing all oils within cobalt bottles and in cool locations can help protect the oils.

Poison

• Cobalt blue bottles were often used for storing poison, such as tablets of mercuric chloride (a pesticide or preservative). Antique cobalt poison bottles had distinct shapes or designs that allowed the owner to distinguish them from other bottles. The bottles had skulls, owls, or diamond-shapes embossed on them and they were often coffin-shaped, making their designs a warning or a message that the contents were poison, in case the label was removed. The cobalt blue glass protected the poison from harmful sunlight that would deteriorate the poison's effects over time.

Medication

• Cobalt blue bottles have been used for a variety of liquid medications, such as cough syrups and Phillips Milk of Magnesia. Cobalt bottle vials are also used for pills that need protection from the sunlight. Antique cobalt bottles, such as Bromo-Seltzer Emerson Drug Co. in Baltimore, Maryland, were suspected to have been sealed with a cork. The medication name or company was often embossed on the bottle.

Milk

• Cobalt blue jars or bottles were also used for milk by the Hotel Sherman in Chicago, Illinois, in its College Inn. The Inn opened in January, 1911, and was a popular restaurant in Chicago during the 1910s and 1920s. The restaurant was still up and running in the 1940s, as it was known for its jazz performances and for ice skating exhibitions. The cobalt bottle was embossed with Hotel Sherman on one side and College Inn on the other. You can view the bottle at DairyAntiques.com.