Brief overview of Hemingray Glass Insulators:
Hemingray was the world largest manufacture of glass insulators. The earliest Hemingray insulators are likely lightning rod insulators from the late 1850's. The last Hemingray insulator was made in 1967. Over the 100+ years of production, they made billions of insulators, in-fact in 1937 they had made there billionth Hemingray insulator! They continued to produce insulators a full 30 years from this date, the scale of their manufacture is quite impressive, even by modern standards.

Threadless:
Little is known about Hemingray manufacturing of threadless insulators. They most likely made several styles, but more research is needed to prove this. On style we know of is the CD 732.2 “Floyd Patent” (May 14, 1867 - Patent No, 64,654) it had a pin that snaps in o a groove at the very top of the insulator.

Threaded Pin Type:
On December 19, 1871 Robert Hemingray receives a patent for the molding of telegraph insulators. (Patent No. 122,015) for improvement in molding telegraph insulators. The CD 127.4 and CD 131.4 and CD 133 are likely the early made threaded insulators using this patent (the CD 127.4 is shown in the patent application).

On May 2, 1893 Hemingray received a patent (Patent No 496,652) for "teats" or what we call "drip points" This would become an iconic feature of Hemingray insulators. The Idea was it would help encourage the water to drip off the insulator.

In 1933 Owens-Illinois buys Hemingray Glass Co. For $1,000,000. They continued to use the Hemingray name as it was the dominate name in the insulator world. They promptly started to add date codes to the molds, something that was not on previous Hemingray insulators. In 1933 they aded a 0 to the molds, 1934 molds had 0 _ 4 added etc.

In the early 1930's they were starting to make insulators in an "ice blue" or "ice green" in attempt to make them clear glass. In 1936 this switched to a more "true" clear. As the ice color was not acceptable for making the glass building blocks.

In 1952 Kimble Glass Co. takes over the Hemingray division to produce Kimble power insulators.

The last Hemingray insulator was made in 1967.