Good question. There are many different aspects of insulator collecting. Some like to collect by color, others may collect for the history. Also included are: markings, date codes, age, shape, cd numbers, glass only, porcelain only, etc...Some hoard everything they can get their hands on! Fact is, it's nearly impossible to tell what the collector is looking for. This is why you need to accurately describe your insulator in as much detail as you can.

Choosing the correct category.

Choosing the correct category is vital. You want as many collectors to see your listing as possible. If there is no obvious "insulator section", try searching for an insulator as if you were a buyer and take note of the section. How about categories with names like antiques, collectibles, glass articles, etc..

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Your listing title.

Make sure the word "insulator" is in your title. It's sure to be the first word most collectors will search for, and you don't want to be on the selling end of the dreaded "hidden" insulator. Make sure you spell it correctly, too!
Check out the hidden insulator page!


You may have seen insulator titles with numbers that might start out with CD, U, or M. Such as CD102, U-590, etc. If you don't know the number for your insulator, don't worry too much about it, the collectors buying it will. If you want more information on CD numbers and identification, buy the book that all glass insulator collectors own:
Price Guide for Insulators: A History and Guide
to North American Glass Pintype Insulators
John and Carol McDougald

For more information on U and M numbers and identification for porcelain insulators, this site and his books are the place to go:
R=Infinity - Unipart and Multipart Porcelain Insulators
Maintained by Elton Gish

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Insulator pictures.

I, and most other collectors, would only buy insulators without seeing a picture from a well known collector or friend. A good picture is crucial to selling your insulator.
Use a white background to show the best color. Collectors are aware of different backgrounds, lighting sources, different computer monitors, etc, and how they can affect the color of the insulator in the photo. More on this in the color section.
Several different views are great but not really necessary. If you are only adding one picture, you should hold the camera at the same height as the insulator to show the best profile. This is so collectors will be able to correctly identify the insulator. Any of the descriptions below can be inhanced by a picture, but could take some time experimenting with several angles, camera settings and light sources.

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Insulator measurements.

A few insulators are the same or close to the same shape but different sizes. Measurements are especially important in identifying porcelain insulators. Also, you may have an odd insulator that is not yet listed in any book. It is a good practice to always include the width and height. Measure the overall width across the insulator's base and the total height from base to dome.

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Insulator material.

Well, this sounds like a "no-brainer", but a few insulators have the same or similar shape, but made from different materials. If you don't list what it's made of and it isn't apparent from your photo, you will get asked. The most common materials are glass, porcelain, plastic and rubber. Also notable are some wood, iron, and composition insulator materials. Good idea to note the material in your title or description.

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Insulator color.

Whoa, man, I hate this section. I have decided that plain ol' aqua is my favorite color!
Anyway, this is very important to a lot of collectors, and above all the hardest to describe.
To barely scratch the surface:
Some glass colors are aqua, clear, green, blue, cobalt blue, purple, sage, celery green, hemingray blue, blue aqua, green aqua, off clear, smoke, gray, amber, golden amber, emerald green, lemon, yellow, and on and on and on.....
Add prefixes...light, dark, ice (ice blue is clear with barely a hint of blue)
And dont forget tint...blue tint (more clear than light blue but darker than ice blue)

Some porcelain insulator colors are brown, white, dark brown, sky, gray, blue, green, mustard, yellow, red, butterscotch, red-brown, chocolate-brown, etc.
Further descriptions include tiger stripes, streaks, mottling, speckled, and more.
Some glass and porcelain insulators have two or more distinct colors.

Plastic insulators are usually white or black.
Rubber insulators are usually black.
Wood insulators are usually wood. lol


Colors are affected by your monitor, background, light sources, your camera settings, different light angles, blah, blah... The best way to see and judge the color without going crazy for glass insulators is to hold your insulator up in a well lit room with a white background. If the glass insulator is so dark you can't see through it, then try placing a white light directly under or behind it to shine through.
It may be helpful to use a well known object of the same color to describe it. I have seen Windex Blue, Sky Blue, Pea Green, etc.

Remember...
Even after you have chosen an accurate color to describe the insulator as you see it on your monitor, the collector's monitor may show a different color. This is why you should try to be as accurate as possible with your color description.
Above all, just do your best and over time it will get easier.

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Insulator features inside glass.

Milk, amber, fizz, specks, snow, streamers, bubbles, seed bubbles, junk: all of these are just a few common anomalies found inside insulators as described by collectors. A lot of folks are looking for nothing but the cool special effects and character given to insulators by these features. Without getting too detailed I will attempt an explanation of each:

Milk: looks like milk suspended inside the insulator in the form of

small traces, lines, bands, streaks, waterfalls, swirls, tadpoles
and the big globs, affectionately known as snot


Amber: reddish or brownish color inside the insulator in the form of

small traces, lines, bands, streaks, globs, etc.


Fizz: when tiny bubbles are so concentrated it appears to be fizzing,

almost like a beer or soda


Speck: I use this term to describe any tiny particle that obviously

isn't a bubble


Snow: a high concentration of tiny white specks


Streamer: a flowing line of very tiny bubbles


Bubble: trapped air inside the glass bigger than seed bubbles


Seed Bubble: a tiny bubble about the size of a pin head


Junk: any object that can't be identified embedded inside the glass

If your insulator has any of these features, it is a must that you list them, as they always raise an eyebrow or two.

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Insulator surfaces.

Insulator surfaces are usually smooth and uniform, except of course, for the mold lines and straw marks. Straw marks refer to the creases or indented lines that snake across the surface of a lot of glass insulators. These were made during manufacture and are not considered damage. If straw marks are extreme you should list them as such.
Occasionally, you may come across one that has a rough textured surface all over. Some glass insulators have this whittled look, as if they were whittled out of a block of wood with Grampa's pocket knife. Consider this surface effect a bonus and list it.

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Insulator base types.

The base of an insulator is the bottom surface as it sits upright. A few different types and their description are:

Smooth Base: a base with a smooth surface

Corrugated Base: smooth base that has intentionally been textured

Rounded Base: smooth base that has a rounded edge around the outside

Sharp Drip Points: base with cone shaped projections or "teeth"

Round Drip Points: base with ball shaped projections or "beads"

Flat Drip Points: base with drip points that have been flattened on the end

Continuous Drip: base that is higher on one side than the other and actually causes the insulator to lean

Wedge Drip Points: base with wide wedge shaped drip points

Corrugated Drip Points: base with corrugated or "ribbed" drip points

Grooved base: Smooth Base with a continuous V-shaped groove in the middle

Base Embossed: smooth base with embossed markings

Base types can be deceiving, even with great pictures. Describing the base avoids confusion.

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Exact insulator markings.

Finally, my favorite. Markings on insulators are important. Date of manufacture, mold numbers, style numbers, company names and more can be learned from an insulator's markings. You should type your markings exactly as you see them. If you come to a symbol, logo, backwards number, just make a note to describe it. You should be familiar with these basic locations of insulators.

Dome - Very top section of an insulator

Crown - Section of insulator between dome and wire groove

Wire Groove - Continuous groove around outside of insulator

Skirt - Section of insulator from wire groove to base

Base - The very bottom surface of an insulator

Now that we got that out of the way, it is just as important to say where each marking is located. As in:

Dome: 3
Front Skirt: HEMINGRAY-71
Rear Skirt: MADE IN U.S.A.


If there is more than one line on a single location, use some fancy html, note it or just use a slash (/):

Front Skirt: WHITALL TATUM CO.-98 (WT in a triangle)/Made IN U.S.A.
Rear Skirt: PATENTED/MAY 7, 1636

note: the (WT in a triangle) above is the logo for Whitall Tatum Co.

Also, make sure to get all the periods, quotation marks, dots, symbols, or any other type of marking accurately described. I could go on forever about markings, but that would take, well, forever. Browse the EIM lists to get an idea of what other listings look like.
EIM HOME

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Insulator marking types.

While nearly all glass insulators have the embossed type marking, porcelain insulators have many different types of markings. It is a great help in determining the age of the insulator if you describe the marking type. The most common types of markings are described below.

Embossed: raised from the surface of the insulator

Incuse: recessed into the surface of the insulator

Under-glaze: for porcelain insulators, ink stamp under the glaze.

Sand Blast: for porcelain insulators, made by sand blasting the finished insulator to make a dull marking

Recessed-embossed: has a recessed area surrounding embossed marking

Slug-embossed: embossed onto a raised surface or band

Insulator damage.

All damage should be listed. Below are some of the common terms used by insulator collectors and an explanation of each.

Fleabite: tiny dimple or pock mark about the size of a pin head on surface

Scratch: line on surface from abrasion

Wire Rub: material worn off on or near wire groove

Roughness: any spot where the insulator doesn't seem to be as smooth as it should

Chip: small chunks of material missing

Chunk: larger pieces of material missing

Flake: thin sliver or slice of material missing from surface

Bruise: material has been impacted and cracked but no missing material

Crack: line in material from stress, no missing material

Open Bubble: bubble that is on the surface or close enough to the

surface as to have made a hole in the material

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Fake, Altered, Repaired, etc.

If your insulator is, or you think may be fake, altered, repaired or anything other than an original and authenic insulator, you have to list it as such. Anything less would be dishonest and, under certain conditions, could be punishable by law. At the very least, any type of dishonest deals travel the collecting community very quickly.

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