"The name LOWEX (standing for Low Expansion--Low Expense) was the trademark registered to Owens-Illinois Glass Company by the U.S. Patent Office on August 22, 1939. O-I had been embossing the word LOWEX on their power insulators since 1938, while still retaining the "Hemingray" embossing on the insulators produced by their Hemingray Division. O-I had purchased the Hemingray Glass Company of Muncie, Indiana in 1933, and was determined to meet the demands for quality power insulators for the major electric suppliers and distributors of that period.
"LOWEX insulators are unique because of their high heat resistance, high electrical puncture resistance, high mechanical strength, hard smooth surface, and excellent design. Yet, collectors will note that they had a limited production run of approximately four years. LOWEX insulators are found in ten CD numbers, among the colors are clear, ice green, peach and amber (various shades). Some have brass bushed pinholes and some are radio treated in the pinhole and wire groove. Contrary to the claims of some, LOWEX insulators are not found in aqua or in carnival.
"It is interesting to note that O-I continued the power insulator line that Hemingray had successfully developed prior to 1933, and even experimented with carnival treatment prior to the development of the new LOWEX glass formula. They also continued to produce the same CD's following the ending of the use of the LOWEX trademark on insulators until at least the 1950's. So, what happened to the use of LOWEX glass? Some theories are: (1) the particular extra ingredients used in batch formulas were costly, (2) those extra ingredients (possibly led, boric acid, magnesium, etc.) were needed for the war effort (WWII) or because in short supply, or (3) a shortage of labor, and the difficulty/expense of maintaining an extra furnace(s) caused O-I to make all their power insulators out of the same glass used to make communication insulators, bottles, etc."