Below is a glossary of terms related to Hemingray insulators that are used throughout this web site that you might not be familiar with. Some of these terms were used back when Hemingray insulators were manufactured, and some were coined by and are used by the insulator collecting hobby today.
Blot-out: A blot-out is where there was once an embossing on the insulator, but it was later removed from the mold. A blot-out will often leave a tell-tale "rough area" where the embossing once was (due to the area of the mold being gouged out and filled back in). Some blot-outs were so poorly done you can still see some or all of the embossing. Hemingray would often blot out and stamp over old embossings (such as if they were re-using an old mold). Blot-outs would also often be used to correct embossing errors.
CB: Stands for Corrugated Base. Many of Hemingray's insulators produced in the 1950's or later bore this type of base, which has a rough, "cross-hatch" feel.
CD Number: CD stands for Consolidated Design number. This is a numbering system developed and used by the insulator collecting hobby to identify and differentiate between the hundreds of different insulator styles. These numbers do not appear anywhere on the insulators themselves.
Drip Points: Drip Points, originally called "teats" by Hemingray, are "bumps" on the bottom of some insulators that were designed to draw condensation off of the insulator. Hemingray was granted a patent for this concept on May 2, 1893. Hemingray made two types of drip points: the earliest type was SDP (Sharp Drip Points), and later RDP (Round Drip Points).
EIN: Stands for Embossing Index Number. This is a number that corresponds to the specific embossing of an insulator, making it easier to identify the embossing. It is usually shown in brackets, such as: [030]. This number does not appear anywhere on the insulator itself.
Floor Tube: A floor tube (also called "wall tube" by some collectors) was a type of glass insulator manufactured by Hemingray. These were designed specifically to fit through a hole in the floor (or wall) to allow a wire to pass through, while insulating it on all sides. These are not currently assigned CD numbers. See the
Hemingray Floor Tube page for more information on these.
H.G.CO.: Stands for Hemingray Glass Company. Many of Hemingray's earlier insulators were embossed with "H.G.CO."
Kimble: Under the ownership of Owens Illinois, Hemingray manufactured several power insulator styles under the "Kimble" trademark.
LOWEX: This was a trademark that was embossed on some of Hemingray's insulators beginning in 1941. It stood for "Low Expansion - Low Expense", which described the properties of the new glass they were marketing at the time.
Mine Insulator: A mine insulator was designed to be used inside of mines. Similar to a spool style insulator, it has a hole through the top and bottom, and is usually threaded. According to U.S. Patent #
526498, a special mounting pin would be driven up into the rock of a mine. This pin had a hole through it, so when water would drip down it could channel out through the bottom of the insulator, preventing the water from shorting out the circuit.
CD 185 is an example of a mine insulator.
MLOB: Stands for Mold Line Over Base - The mold line extends to the inside edge of the base, but there is also a mold line near the bottom of the skirt as well. This type of mold can be found on some of the Patent Dec. 19. 1871 embossed Hemingrays.
Owens-Illinois: Owens-Illinois was (and still is) a very large glass manufacturer that purchased the Hemingray Glass Company in 1933. Glass insulators continued to be manufactured under the Hemingray, Kimble, and Owens-Illinois trademarks at the Muncie, Indiana factory until around 1966.
Patent April 25, 1899: This patent was granted to Vernon G. Converse for a specific design for a high voltage power insulator. It was assigned to Hemingray, and all of the "Provo Type" series of Hemingray insulators bear this patent date.
See related patent.
Patent Dec 19, 1871: This was the patent granted to Robert Hemingray for a special press for forming threaded insulators. Many of Hemingray's earliest insulators bear this patent date.
See patent information.
Patent June 17, 1890: This patent was granted to Samuel Oakman for a special type of insulator that had "ears" for which to assist in tying down the wire. Some Hemingray
CD 257s bear this patent date.
See related patent.
Patent May 2, 1893: This was the patent granted to Hemingray for drip points (called "teats" at the time), intended to draw condensation off of the insulator and away from the inside of the insulator.
See patent information.
Patent Oct 8, 1907: This patent was granted to John C. Barclay for a spiral extension above the wire groove. Two styles produced by Hemingray bearing this patent date:
CD 147 and
CD 150.
See related patent.
Patent Sept. 25, 1894: This is the patent assigned to Joseph A. Jeffrey for the design of a mine insulator. Hemingray manufactured the
CD 185 Special Mine Insulator for the Jeffrey Mfg. Co. A special mounting pin would be driven up into the rock of a mine. This pin had a hole through it, so when water would drip down it could channel out through the bottom of the insulator, preventing the water from shorting out the circuit.
See related patent.
Petticoat: A petticoat is simply the original term for what collectors now call an insulator's "skirt". The more skirts/petticoats an insulator had, the longer the total distance from the wire groove to the pin holding the insulator was. Insulators with a "double petticoat" had two skirts: 1 inner skirt and 1 outer skirt. An insulator with a "triple petticoat" had 2 inner skirts and 1 outer skirt.
Pony: A Pony is a generic term to describe a small style insulator, such as a
CD 102. This term was originally used when insulators were first manufactured and is still used by the hobby today.
RDP: Stands for Round Drip Points. For the most part, this type of drip point was used after SDP (Sharp Drip Points). See also "Drip Points".
SB: Stands for Smooth Base. This term is used to describe the absence of drip points or other types of bases on an insulator.
SDP: Stands for Sharp Drip Points. This type of drip point was used first, eventually replaced by RDP (Round Drip Points). See also "Drip Points".
Spool: A spool is a generic term for any glass insulator that has a hole through the top and bottom, and generally resembles a spool of thread. Depending on the size and design, they were generally used for end of the line ("dead-end spool") or low voltage applications. Hemingray marketed these types of insulators as "Break Knob Spools".
Teats: Teats were the original term used by Hemingray to describe what collectors now call "drip points". Hemingray was granted a patent for drip points on May 2, 1893. See also "Patent May 2, 1893".
Transposition: A transposition insulator was a special type of insulator with two wire grooves that was designed to "swap" the positions of two lines. This would reduce the interference that would otherwise be caused by two lines running parallel to each other for too long a distance.
