Collecting Antique Glass Insulators

Updated on April 23, 2018
Jeanne Grunert profile image

Jeanne Grunert is a Virginia Master Gardener, gardening magazine columnist, and book author. She is a full-time freelance writer.

Three glass insulators.
Three glass insulators. | Source
Hemingray glass insulator.
Hemingray glass insulator. | Source

Glass Insulators

If you've ever walked into an antiques shop and seen funny bulbous-shaped colored glass objects on a table and wondered, "What the heck is that?" the answer is simple; you are looking at glass insulators. What are glass insulators? They were used along old telegraph lines to keep live electrical wires away from the wooden telephone poles. They hearken back to the days of old railway travel, of telegraph lines and the advent of the mass communications age. Today, porcelain and ceramic insulators are favored for modern use, but the beautiful and functional glass insulators live on in the nascent hobby of collecting antique glass insulators.

Whithall glass insulator.
Whithall glass insulator. | Source

The History of Glass Insulators

As railway lines and telegraph lines spread throughout the United States, electricity needed to be carried along powerful cables along those same lines. But live electrical wires and wooden telegraph can't touch - they can start a fire. Electricity conducts through certain materials, but other materials resist conduction. Glass and porcelain are two such materials. Glass insulators were manufactured so that live electrical wires could be strung from pole to pole without the wires touching the wood and starting a fire.

Insulators are made from glass, porcelain, rubber, and sometimes other materials, but the ones you see most frequently at antique stores, flea markets and yard sales are made from glass. The unpainted ones in the images accompanying this article are all glass insulators in my own little collection. I found mine dumped on the edge of the woods near our farm. At the time I found the box of glass insulators, the old Norfolk-Southern railway line nearby was decommissioned and the state was transforming it from an abandoned railway line into a multi-purpose recreational trail. While you can still see some of the listing and leaning old telegraph poles along that same trail with the green, blue and white insulators winking along the cross arms, most of the insulators have either fallen off or been removed over time. I suspect that my group of insulators may have been collected from along that railway bed.

Major Types of Glass Insulators

Glass insulators come in a fascinating array of colors, sizes and shapes. The major producers of glass insulators during their heyday included:

  • Hemingray - Hemingray produced glass insulators from 1848 - 1972. Their website offers a guidelines for identifying your Hemingray insulator and the approximate time period of production. Hemingray stamped the glass with the company name and many Hemingray insulators also have an identification number, indicating the type, stamped near the name.
  • Whitall Tatum
  • Pyrex
  • Dominion
  • Many others

Glass Insulator Shapes

Insulators come in a wide variety of shapes and sizes. Most have a depression or indentation in the center. This is how the insulator fitted onto the crosspiece of the wooden poles lining the railway line. They were threaded onto pegs and glued into place. Insulators typically have a space for the wire or a threader near the top. The electrical wire was threaded and looped around this section.

Some insulators have glass 'teeth' along the bottom ridge, perhaps to help them grip the wood better once placed into position. Others have a smooth edge.

Colors of Glass Insulators

Glass insulators come in a wide range of colors. You will find:

  • Clear
  • Light aqua
  • Aqua
  • Cobalt Blue
  • Ruby red or Amber
  • Peacock of "Hemingray" blue (named for the manufacturer)
  • Green
  • Purple

Why were different colors made? Railway lines often shared the right of way with several companies. According to Insulators Info, a 1909 catalog listed various colors of glass insulators to help the linesman distinguish which insulator and line belonged to which company. Company A may choose clear, while Company B used only Hemingray Blue, etc. The colors varied even among similar colored insulators listed for sale in manufacturer's catalogs, and a wide variation may be found among similarly colored insulators from the same company.

Identification and Value of Glass Insulators

Most collectors agree that the best way to identify and determine the value of a glass insulator is to begin with whatever markings are on the piece itself, and to use a good price guide and identification book. Although the hobby of collecting glass insulators is fairly new, there are many good books out on the market that can help you identify and price your glass insulator.

As with most glass antiques, condition and rarity are most important to determining value. Cracks, chips or damage of any kind on a glass insulator decrease its value significantly. In most cases, rarity, rather than age, also impact value. The insulators I found along the edge of the wood had cracks and chips and when I looked them up, were all very common insulators, making them worth very little. When in doubt, check the price guides.

Painting a glass insulator can destroy its value.
Painting a glass insulator can destroy its value. | Source

Collecting and Displaying Glass Insulators

The hobby of collecting glass insulators is a fairly new hobby, but there are collectors worldwide. There's even a club, the National Insulator Association, to encourage collecting. There are events, meetings and more.

You can find glass insulators for sale on eBay, at flea markets, yard sales, auctions and antique shops nationwide.

Glass insulators in perfect condition are best left as they are. They can be displayed on a shelf or on a windowsill. Mine make beautiful 'stained glass' effects from their place of honor on the windowsill. Some people paint the very common or damaged ones to make them into pretty paperweights, like the sunflower one shown here that I bought on eBay. Before transforming your glass insulator into a craft project, be sure you are certain of its value and are willing to part with it, because once transformed it loses any inherent value it had as an insulator.

Collecting glass insulators is a fascinating hobby. It's a glimpse back into time, when coal-fired engines chugged along railway tracks and telegraphs clicked out messages to waiting towns.

© 2012 Jeanne Grunert


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    • profile image

      Victoria Hausmann 

      2 weeks ago

      I have a yellow crackle glass insulator. I have never see one like I have. Can you help me find out where it came from and if it is worth anything?

    • profile image


      2 months ago

      I have a bunch of insulators,glass, porcelain, plastic in the garage. How do I find someone that would buy them?

    • Jeanne Grunert profile imageAUTHOR

      Jeanne Grunert 

      3 years ago from Virginia

      There are a few enthusiasts, but I think it's pretty much a niche hobby. Thanks for stopping by!

    • MichaelMcNabb profile image

      Michael McNabb 

      3 years ago from Oconto, Wisconsin, USA

      Do you think people are still actively collecting insulators? Some family of mine (My parents) ran an antique store from 2006 until last year and they had dealt with quite a few insulators but never a lot. I guess with anything the more unusual the better.

    • Seasons Greetings profile image

      Laura Brown 

      3 years ago from Ontario, Canada

      I used to have some of these, two were blue and one was clear glass. I knew they were insulators from the telephone poles but not a lot beyond that. I still watch for them on phone poles when we are out driving.

    • FlourishAnyway profile image


      5 years ago from USA

      Enjoyed your hub. We've seen these hiking near a railroad trail a few miles from our home, and while I knew their general purpose I did not know all the details. Thanks for your fine research on them.

    • Jeanne Grunert profile imageAUTHOR

      Jeanne Grunert 

      5 years ago from Virginia

      We have an old rail trail (an old railway line made into a hiking trail) near us and you can still see them glittering on top of the crumbling T-poles. Love them. I love things that are both decorative and highly functional. Thanks to all who have left comments!

    • Ira Mency profile image

      Cindy Fahnestock-Schafer 

      5 years ago from Hedgesville, WV

      I love these things, and find them still down in Virginia near the old tracks by Mt. Jackson. Thanks for sharing.

    • grandmapearl profile image

      Connie Smith 

      5 years ago from Southern Tier New York State

      I have a collection of these insulators, clear, aqua and green. My grandfather once worked on the railroad that wasn't too far from our rural home. I have been wondering about these insulators for a long time. Thank you for sharing this valuable information. Voted Up, Beautiful, Interesting and Useful--also shared.

    • Dolores Monet profile image

      Dolores Monet 

      6 years ago from East Coast, United States

      Oh I love glass insulators! They are so pretty. I have a couple and really knew nothing about them, so I certainly enjoyed this hub.

    • PenHitsTheFan profile image

      Amy L. Tarr 

      6 years ago from Home

      My Dad had some in his basement when I was a kid. I never knew what they were,so thanks for the info.

    • AM Hanson profile image

      Adam M. Hanson 

      6 years ago from Mankato, MN

      my brother collects them, it's fun when he shocks people by recognizing them at rummage sales

    • moonlake profile image


      6 years ago from America

      I just saw four glass insulators at a rummage sale on Friday. We don't buy them anymore. We had a few our daughter took those and she puts them on her bookshelf. Enjoyed your hub and voted up.


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