Antique insulators can be very valuable. These insulators were used on telephone and telegraph poles beginning in 1844 and were usually made of glass or pottery materials. Threadless insulators made between 1850 and 1870 are highly desired by collectors.
The production of insulators used to protect the wires on telephone poles from the wooden pole structure peaked during the 1920s and 1940s. These insulators were made in a wide range of colors and shapes, including purple, green, blue and amber. The most common colored glass used for antique insulators was either clear or shades of aqua blue. The value of each antique insulator depends on a number of factors, including condition and rarity.