Jun. 05, 2025
New to the hobby? Be sure to read Ted’s Top Ten Tips For New Insulator Collectors.
You can find more information on our web, so please take a look.
Want to know more about glass making? Read Frequently Asked Questions about Molding Glass Insulators.
Tip: You may also want to consult the Glossary of Insulator Terms.
If a picture is worth a thousand words, you should take a look at a few photographs of insulators in service!
The need for the insulator arose out of the discovery of electricity, which in turn led to the invention of the light bulb, telegraph, , and other electricity-oriented innovations. Also, as railroads began crisscrossing the continent, there came the need for signal devices. Electricity had to be moved economically from one place to another to meet the increasing demands generated by these new marvelous inventions.
According to Webster, to insulate means "to separate or cover with a nonconducting material in order to prevent the passage or leakage of electricity, heat, or sound." Communication and electric line wires in service must be kept as dry as possible in order to function efficiently, and to cut down on loss of current. The wires are kept off of the ground by being strung between poles. But something was needed to keep the wires and (sometimes wet) poles apart. This "something" had to meet three basic needs:
This "something" was the insulator. It was developed and improved upon over the years to meet those basic requirements and:
Often, one will have to consult the reference books to determine the CD number of an insulator. However, many newer insulators have a style number embossed on them, and one can look up that style number in this Manufacturer and Style Number to CD Number Chart.
Pintype insulators are grouped by a number of different characteristics:
There are also non-pintype insulators, which include spools, dead end insulators, and wire strain insulators.
Insulators were developed over the course of more than 100 years, for a variety of applications including telegraph, , and electric power distribution. Many shapes evolved to hold the line wire more efficiently or to increase the insulating ability. Larger insulators were developed to meet changing needs as larger heavier wires or higher and higher line voltages were used. In addition, some insulator shapes were designed for special applications. Many insulator companies would patent special shapes, designs or other attributes, even if in reality the invention proved impractical. Take a look at some of the varied shapes of insulators.
In general, insulators were not made in specific colors for any reason. The natural materials that were used to make glass, including sand and glass cullet, tended to make light aqua to aqua colored insulators. Some batches were more green, others more blue. In addition, some trace chemicals would alter the color of the insulators. Also, since all glass is produced using some glass cullet, the composition of the cullet would also have an impact on the color of the resultant insulator. Take a look at some of the varied colors of insulators.
Special colored glass insulators were produced in only a few cases. A Electric Appliance Company catalog gives this description:
Where several lines of different companies are on the same cross arm the lineman can distinguish his line by the color of the insulator. Different currents can also be designated by different colored insulators. We are prepared to furnish all styles of [Hemingray] insulators in red, blue, and amber glass, but shipments can be made direct from the factory only.
Add per M for colored glass . . . . . . . . . . . . . . . $8.00 net
It is interesting to speculate about what was meant by "red" colored insulators, given that "amber" colored insulator are also mentioned. "Blue" colored insulators probably refer to the bright Peacock Blue or the darker Cobalt Blue colors, and not what we call "Hemingray Blue" today.
In , prices ranged from $38.70 per 1,000 for No. 9 Pony Insulators (CD 106), to $154.00 per 1,000 for Cable Insulators (CD 257), to $1.00 each for a No. 0 Provo Type (CD 249).
There are many factors that determine an insulator's value. Shape, color, embossing, condition, desirability and rarity all affect its value. Most insulators are quite common and have little monetary value. The first step in determining your insulator's value is to determine which insulator you have. Even with a price guide in your hand, you have to determine which of the approximately 460 shapes, different embossings, and almost color combinations best describes your insulator. (And those numbers don't even include any foreign or porcelain insulators!) It is easy to list the common insulators, and also list the very rare insulators, but it is difficult to list all the thousands of collectable insulators that fall between those extremes! A slight difference in the shape of your insulator can affect its value by twenty fold or more. A slight difference in color can also significantly affect the value of your insulator. Unless your insulator is either very common, or very rare, it is best to consult a knowledgeable insulator collector or dealer; or to educate yourself and invest in one of the good insulator books available. If you are serious about collecting insulators, getting a good insulator reference book is a "must".
The two obvious ways to add insulators to your collection are either to find them, or to buy them. Finding insulators "in the wild" can be difficult, and if you find some, there is a good chance that they are common insulators. Most collectors buy (or trade) insulators. Many beginning collectors may find insulators at antique stores, flea markets, and the like, but you will soon realize that your section is very limited, and the insulators are generally overpriced. Although, there is a remote possibility of that rare bargain!
I believe the most effective method to add new insulators to your collection is to obtain them from other insulator collectors. A few years ago, I did an analysis of where we got our insulators from over the previous 6 years. I found about one third of them we bought from ads in insulator magazines, another third from writing for "for sale" lists also advertised in the insulator magazines, and the last third from insulator shows. Not much can top a good insulator show! You get to see a wide variety of shapes and colors, as well as prices! You also get to see exactly what you are buying. It is your opinion of the color, condition and other attributes of an insulator that matters. What better way than to hold it in your hand and look at it? Look at these show listings to see if there are any shows coming to your area. You might also want to check with your local insulator club for additional information. Insulator shows have one other thing going for them -- the people! The people are what make the hobby fun! Meeting collectors and dealers at shows is a great way to learn more and make new friends!
On the Internet, there are a number of insulators for sale pages posted, as well as the Insulator Finder! where you can register your wants and automatically be sent when insulators matching your wants are posted for sale!
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Last updated Sunday, August 31,
The "Ten Tips" listed below are suggestions for new insulator collectors, based upon my own experiences. Some of them could have a whole page devoted to them, but rather than do that, I have attempted to be brief and give you just enough to convey the idea. The Case Study is factual, and serves to illustrate the importance of some of my advice.
Link to ZheXi
Several years ago I noticed a classified advertisement in my local newspaper about an insulator collection for sale. I contacted the seller on the , and made arrangements to see him and his collection. My goal was to buy the collection if it was a decent one, as I was a relatively new collector at the time, anxious to expand my own collection. The below are the salient details of my visit and observations:
My impression was that the seller needed to sell his collection because he and his wife had recently purchased a new house, and needed the money to finish the yard – landscaping, fences, etc. Although he was personable, I tactfully declined to buy the collection. About six weeks later I was again reading the classified ads, looking for insulators to buy. I saw an interesting ad and called the number in it. It turned out to be the same seller – I hadn’t recognized his number, and he still hadn’t sold his collection.
New collectors should try to find a more experienced collector, and then use that collector as a mentor. Most of us are flattered by someone asking questions about a subject that we know something about. Don’t be bashful about telephoning a collector and inviting yourself over after you’ve explained that you’re a new collector -- insulator collectors are some of the most friendly and generous people that you’ll ever meet. Preferably, your mentor should be a local collector so that the two of you can occasionally visit each other. The experienced collector can offer advice in the form of education, and advice about what pitfalls to avoid. When I was a new collector, I was fortunate to have several established collectors to buy insulators from at attractive prices, to volunteer general information and advice, and to answer questions.
Secondly, insulator collectors are almost always pleased to have someone take an interest in their hobby – few people do, including their ‘significant others’. Therefore do not be surprised if your potential mentor wants to show his/her collection to you – use the opportunity to ask questions and acquire knowledge about insulator collecting. Pick the brains of the collector, with the goal of learning as much about insulator collecting as he/she does. And remember that ‘no question is a stupid question’, and ‘if you ain’t asking, you ain’t learning’.
Insulator collecting is a highly organized and detailed hobby, with its own terminology, identification systems, price guides, history and practices. Therefore you must possess a certain amount of knowledge for you to know what it is that you’re collecting, to assist you in collecting, and to communicate knowledgeably with other collectors. To be able to do that, you have to acquire the reference books applicable to that portion of insulator collecting (glass or porcelain) that you’re interested in. You’ll find that after a short period they’ve become invaluable tools that have paid for themselves. Some common examples illustrate why you need the reference books:
Regard your collection as an asset that will appreciate in value over time. Whether insulators will appreciate in value and be investments is debatable, and I’m not suggesting that will happen – I honestly don’t know. But you should acquire insulators with the view that you may want to sell or trade them in the future, and hopefully recover most of your acquisition costs if you do. Therefore buy the best insulators that your budget can afford, particularly with respect to their physical condition. Most insulator are not ‘mint’ and we all have to have some damaged insulators in our collections (e.g. I have yet to see a CD 196 insulator for sale/trade that was in good physical condition). But establish a standard of acceptable physical condition for your collection and budget, and then stick with it. Many collectors will buy damaged insulators and then ‘upgrade’ them in the future when the opportunity arises. If you do the same, pay a price for that first insulator that is commensurate with the damages.
With the recent parcel rate increases by the American and Canadian post offices, shipping costs are becoming a significant portion of insulator acquisition costs. Because insulator collectors reside all over North America, with a few overseas, insulator acquisition frequently requires that they be sent by mail or commercial courier. When you’re buying or trading for insulators that have to be shipped to you, keep in mind that the first one in a parcel is the most expensive to ship, and the last one is the cheapest. This is because of the way that the parcel rates are structured – the last weight increment is the cheapest. While this may sound like common knowledge, I still come across collectors who buy one or two cheap insulators at a time, and then have the postage to send them equal or surpass their value. This is important, because the convention is that the buyer pays for the shipping costs. I recently quoted a collector $4.48 for postage costs to send the one small insulator that he was interested in. But to send him a parcel of four insulators, the postage costs were only $7.82 – obviously ‘more is better’ to lower average shipping costs.
Therefore if you’re acquiring insulators where you have to pay the shipping costs, buy a sufficient quantity to minimize your average shipping costs. To do that, try to patronize those sellers that are selling at least a couple of insulators that you want to acquire – try to get the biggest bang for your shipping dollar. Avoid buying from sellers that only have one insulator of interest to you. Of course, there will be times when that is not always possible because other considerations will over-ride the economics. An example might be that you’ve finally found a scarce insulator that has been difficult to acquire in the past, and it could be a long time before it becomes available again.
The current price guide for North American glass insulators cites over 9,000 different insulators – different because of the different combinations of CD numbers, colors, primary embossings, and specific embossings. Granted, the differences between some are subtle (e.g. the difference between two specific embossings might only be one having periods after abbreviations, and the other one doesn’t). But if we include the differences that the price guide doesn’t address, such as the different variations in the color ‘aqua’, then the number becomes larger. And then if we include foreign glass insulators, porcelain insulators, and insulator related items (radio strains, guy wire strains, dead-end spools, knobs, etc.) we’ve got a huge number that is not yet known.
My point here is that no collector has the time and money to acquire all insulators, and the space to display or store them. Therefore I suggest that after you’ve acquired enough information about insulators to know roughly what there is out there to collect, start to consider specializing. There are many ways to specialize, so I won’t get into them in this brief article – just establish some collecting criteria once you know what appeals to you the most. Not all collectors specialize – many just acquire insulators that appeal to them, and there’s nothing wrong with that – instead of a collection that has a theme, their collections are eclectic. But the advantage of specializing is that it functions as a screening process for insulators that are outside of your collecting criteria. There is no shortage of insulators to acquire, and it’s tempting to acquire many of them -- but if they are not within your specialty, resist temptation and use your money or traders to acquire those that are.
It is important that you communicate with other insulator collectors. I have met a few insulator collectors who have been collecting in isolation, and it’s been a frustrating experience for both of us. From my perspective, they have no knowledge about the hobby -- supply sources, contacts, new developments, current prices, and terminology. The above Case Study is about such a collector. The advantages of communicating with other collectors are the following:
You can be part of the insulator collecting community by any one of the following:
When I was a new collector there were several occasions when I purchased insulators from antique shops and flea markets, only to find out later that they were duplicates of what I already owned – I couldn’t remember what I already had in my collection. I then made a computerized inventory of my collection, and took a hard copy of it whenever I knew that I would be insulator shopping. I won’t go into a lot of details, because there is an excellent article written by Bill Meier about cataloging your insulator collection. If you don’t have a personal computer, you can still catalog your collection the old fashioned way – I recommend using a columnar pad purchased from a stationary store.
I strongly recommend an inventory if your collection is 100 or more insulators. My own inventory consists of one spreadsheet for each of my 14 ‘sub-collections’, the total of all of them being about insulators. At a glance, I can determine if I already own a certain insulator when I see a similar one for sale, and if I do, whether I need an upgrade for it or not. I also compare the total acquisition costs of my collection to the total Price Guide values to determine if my total acquisition costs are reasonable or not.
Besides allowing you to know what your collection consists of, an inventory is also advisable for insurance purposes. As an example, if your collection eventually grew to be worth $5,000 (very easy to do) and you then had a house fire or vandalism, the inventory would be invaluable in helping you file an insurance claim. For that reason, you should keep a recent copy of your inventory with your other valuable papers in your safety deposit box.
Like so many other items and activities, the sky’s the limit with respect to the amount of money that can be spent on insulators – prices range from free to thousands of dollars. Therefore it is important that you establish financial limits that are reasonable for your disposable income, and then stay within those guidelines. Ask yourself if your insulator collecting costs are in addition to, or in place of your other recreational expenses. If the costs are in addition to your current hobby and recreational expenses, can you afford insulators?
I am aware of a few collectors that became so enthusiastic about insulator collecting that they forgot about financial common sense, and eventually suffered the consequences. You don’t have to be rich to be an insulator collector – most insulators are priced below $20, and it is possible to build a very respectable collection on a limited budget over time. Trading with other collectors, and buying from flea markets, garage sales and second hand stores will also reduce your cash outlay. Remember that insulator collecting is supposed to be an enjoyable hobby, and not the cause of financial stress.
Most antique stores/shops have a few insulators for sale, and a lot of insulators are actually ‘antiques’ by virtue of being over 100 years old (although many antique dealers have a much more liberal definition of that term). In my area, it is not uncommon to find a $0.50 insulator with a $10.00 or more price tag on it – and it is frequently so damaged that I would throw it away. To be fair to those antique dealers, they have overhead costs that they have to recover, whereas the suggested prices in the price guides are for transactions between collectors who do not have the same costs.
Antique dealers know very little about insulators, nor can they be expected to – their inventory is too vast for them to concentrate on every type of antique. Therefore antique dealers know a little bit about a lot of antiques, but their depth of knowledge about any one of them is very superficial. So beware of misinformation from them – I once had an antique dealer tell me that a Dominion CD 154 was made in because the embossing said ‘DOMINION - 42’. Because insulators are not a big money maker for them, antique dealers don’t spend the time to learn more about them – it just wouldn’t be cost effective. For that reason, occasional bargains can be found in antique stores if you know your insulators and prices well enough – the antique dealer’s price is low relative to that suggested by the price guide.
This tip was suggested by my wife, and after thinking about it, it’s excellent advice. If you have a ‘significant other’ in your life, it’s important that approval for your insulator collecting be given by that person. And the more serious you are about insulator collecting and the more resources that you give to it, the more important that approval becomes. When I initially informed my wife that I was going to collect insulators, she thought that I was joking. And then she started to resent my hobby because of the amount of time that I was devoting to it, and not to activities that the two of us could be doing together. We ended up having many ‘discussions’ about my hobby. And I had to buy a second personal computer for her to use because I was monopolizing our first one, doing insulator related things with it.
Insulator collecting requires time, money and space – not just to acquire and display your insulators, but for related items and activities as well (e.g. reference books, attending swap meets). Therefore make sure that your significant other is in agreement with your hobby -- involve him/her if they’re willing to participate. But don’t let insulator collecting become a source of friction between the two of you – it’s supposed to be a stress reducing hobby!
I have a hard time visualizing insulator collecting prior to personal computers – I know that it was done, but it must have been very time consuming, expensive and laborious. If you don’t already own a personal computer, then insulator collecting is another reason to get one. And if you already have a personal computer, which you probably do if you’re reading this, then use it as tool to assist you with your collection.
I have already mentioned Bill Meier's article about using a computer to catalog your collection. Another major computer use is communication with other collectors. Prior to getting capability, my long distance costs were frequently in excess of $100 per month because of calls to other collectors. Now I rarely call anyone long distance, and then only if I’m calling a person that doesn’t have an address. I buy, sell and trade insulators by and the Internet. I subscribe to the ICON news/chat line, and periodically visit the Glass and Porcelain Insulator Web Site and its links to see what’s new in the hobby. Other insulator related uses for my computer are correspondence, making parcel shipping labels, record keeping and digital photography.
Last updated Thursday, February 4,
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