Lynchburg Insulators

A Collector's Guide

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Insulator Anomalies

Dennis Bratcher

One-of-a-Kind Lynchburg Insulators

Collecting something as functional as glass insulators is not as as easy and "clean" as drawing up lists of style numbers and colors. Insulators served a very practical purpose and were made as cheaply and quickly as possible without much attention paid to neatness or perfection of the product. This results in various anomalies, accidents, and imperfections that made it past quality control, often one-of-a-kind pieces, that provide insulator collectors with a variety of oddities to collect.

These one-of-a-kind insulators are the result of various quirks in the manufacturing process, mishandling of the insulators during pressing or cooling, or other anomalies in their making. It is not unusual for a single piece to exhibit two or more of these anomalies. (click on the name below for examples)

There are other features often found on insulators, such as creases or ripples in the glass, folding marks usually on the crown, or parts of the lettering that did not form. These are not anomalies but are considered a normal part of the manufacturing process.

  • bicolor or two-toned insulators, two very distinct colors,the result of incomplete mixing of two separate batches of glass or the addition of cullet (recycled glass) of a different color that was not adequately mixed. The most common bi-color is aqua and green, which can occur either when green glass is added to an aqua or blue glass batch, or when amber cullet is added to an aqua or blue glass batch and mixes in some areas to produce green. These are not rare in Lynchburgs, but are highly valued by collectors.
  • color swirls, streaks or swirls of color different than the primary color of the insulator, usually the result of inadequate mixing of cullet (recycled glass) added to the glass batch or dissolved foreign material in the glass mixture. The most common are green or amber swirls in aqua. Small amber swirls are often caused by iron oxide (rust) from ladles or other tools used to handle the glass. Color swirls often occur in bi-color pieces. These are not rare in Lynchburgs, although pieces with large or pronounced swirls are highly valued by collectors.
  • milk swirls and jade, white streaks through the insulator, the result of foreign matter dissolved in the glass or the presence of certain chemicals in the glass mixture, perhaps introduced through cullet; in some cases there is enough to give the insulator an opaque or jade appearance. While small milk swirls are relatively common and milk swirls dispersed throughout a piece are uncommon, jade pieces in Lynchburgs are rare and highly valued by collectors.
  • carbon swirls, black ribbons or swirls through the insulator, the result of foreign matter in the glass, often organic material such as sawdust that oxidizes releasing tiny gas bubbles that trap the black residue in the glass. While uncommon, they generally appeal only to specialty collectors.
  • bubbles, either included in the glass or accumulated at the top of the mold resulting in voids in the drip points, the result of air trapped in the glass batch, foreign material dissolving in the glass and releasing gas, or incomplete mixing of the glass ingredients. These occur as single large bubbles, a collection of smaller bubbles, or thousands of tiny bubbles (seed bubbles); all are relatively common, although some collectors value them.
  • included foreign matter, usually pieces of fire brick from the glass furnace, but there can also be small rocks from the sand mixture, nails, screws, bottle caps, or other items. These will often cause cracks in the glass as the insulator cools. Some collectors specialize in pieces with inclusions, especially identifiable objects like nails.
  • dome glass, in which the pin hole is very low resulting in a large amount of solid glass at the top of the insulator. This is caused by the mandrel that makes the threads not being fully inserted into the mold. On later presses, the mandrel automatically adjusted to how much glass was gathered into the mold, so if there were too much glass the mandrel would not be inserted as far leaving more glass in the crown. While not especially rare, these are valued by collectors.
  • underpour, either the glass cooling too fast before it could be pressed fully into the mold, or less commonly too little glass gathered into the mold, both resulting in voids in the insulator, usually around the base; these are rare in Lynchburgs, but are not particularly valued.
  • overpour, too much glass gathered into the mold or a loose fitting drip point collar that allows glass to escape around the bottom of the base, resulting in horizontal "fins" around the base. Often it is accompanied by a rough base where excess glass was knocked off by workers. This is much more common than underpour in Lynchburgs. Usually, a piece with overpour is less valued since it is often chipped around the base.
  • melted, flattened, or misshapen drip points, the result of removal from the mold before the glass was fully set. This can occur on any style but is more common on larger pieces like CD 252. It usually detracts from a piece. Irregular or uneven Drip Points are not considered anomalies since all pieces pressed using that particular collar will have the same drip points (see Base Types).
  • glass folds, are pieces of glass that were too cold in the mold and did not completely blend with the rest of the glass in the press, resulting in folds of glass around an identifiable area of glass. Small folds around the crown often occur as single lines or marks in the glass, usually the result of small stringers left from cutting the glass as it was placed into the previous mold. Glass folds are considered manufacturing defects and usually detract from the value of a piece.
  • sagging, lopsided insulators that are tilted to one side or in which the skirt is oval rather than round. The most common examples are tilted in the middle around the wire groove, the result of removal from the mold before the glass was set. A much rarer example is a lopsided skirt that is more oval than circular, the result of the insulator falling over after removal from the mold and the heavy skirt sagging before the glass set. Both examples are scarce in Lynchburgs, and valued by specialty collectors.
  • kisses, irregular marks or gobs of glass usually on the skirt or dome, the result of two insulators touching before the glass was set. This usually happened as the insulators were placed on trays to enter the annealing lehrs, which "cured" the glass. While not common, they usually detract from a piece.
  • handling marks, irregular impressions, sometimes finger shaped, left by gloves or tongs, the result of handling a piece before the glass was fully set. This usually occurred after a piece was removed from the insulator press and was being arranged on trays to enter the annealing lehr. These are uncommon in Lynchburgs, but usually detract from a piece.
  • ghost impressions, part of the lettering appearing as faint "ghost" impressions in the glass in odd places, usually on the skirt or dome, the result of the insulator coming back into contact with the mold as the mold halves were being removed from the insulator. These are fairly common on pieces made using hand presses and less common with automatic presses. They are uncommon on Lynchburgs but are not especially valued by most collectors.

Other Features

There are other features that occasionally show up on Lynchburg insulators. These are not really anomalies since they appear consistently on molds, but for various reasons do not appear on all pieces made from a certain mold.

  • broken or damaged molds, various defects, the result of some minor damage to the mold. Technically, this is not an anomaly since the defect occurred on all pieces made from a specific mold after the damage. This is rare since molds with damage were dangerous to use and were usually replaced or repaired. Most examples are very minor damage. In some cases molds with minor damage, such as dings and nicks, were repaired and put back into service. Such repairs are visible on the insulator as circle blots, often in odd places. Most collectors do not place much value on these except as a variation.
  • blotches, slightly raised irregular areas on the skirt, the result of thin flakes of the mold metal coming off leaving small irregular voids that filled with extra glass. This occurs as the mold is used and the wear increases with use, so not all pieces made from a specific mold exhibit the same pattern of blotches. These are most common on CD 154, although they occasionally occur on other molds as well; some molds were retooled to smooth the flaked areas and recut the lettering. These usually do not affect value.


Color Swirls

Milk and Jade

Carbon Swirls



Dome Glass



Drip Points

Glass Folds





Damaged Molds