From Brass Armadillo Employee Christina Errington,
(This is my first blog ever, it was originally posted on www.iantique.com) 
Insulators, what are they, what were they used for, what were they made of, and are they of any value?
Glass insulators were first produced in the 1850's for use with telegraph lines. As technology developed insulators were needed for telephone lines, electric power lines, and other applications such as railroad signals. In the mid 1960's a few people began collecting these antique insulators. Today there are over 2000 collectors. Production for porcelain insulators started in the 1850’s and 60’s. Porcelain insulators were more commonly used for power distribution due to their greater strength and surface resistance; by 1915 they basically replaced all glass insulators on electrical lines. Popularity has increased for porcelain insulators over the past ten years thanks to the rise in glass prices, earlier ‘classic’ porcelain being taken out of service as utility distribution voltage increases and the increase of available information on the web and in books.