History of the CD 155 KERR DP1 Cobalt Splotch

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In 1972, Calvin Cobb, Sr., a friend of insulator collector Don Wentzel, was instrumental in a project to make the "cobalt splotch" Kerr DP1 at the Kerr factory in Millville. Calvin was a "traffic" manager at Kerr, which meant that he was involved in coordinating the purchasing, delivery, and receipt of all non-glass making material. He also scheduled delivery of finished products with trucking firms and the railroads. While he himself did not work on the line, he was senior enough that many people at the factory owed him favors. As a result, he was able to orchestrate the production of the splotches (and the iridized DP1s). Although many people claim involvement with this project, Calvin was the driving force behind it. It is interesting to note that Alex Kerr, the president of the Kerr Glass Company at the time, was not originally aware of the production of these insulators. He did not find out about them until many years later, after Calvin retired.

The insulator making machines in use at Kerr received glass from the main batch through a feeder. Additional material could be added to the glass batch in this feeder before delivery to the insulator forming machine, and went through a pair of stirrers that made sure all the material was combined properly. The cobalt splotches were made in the middle of a clear glass run, and adding material directly to the feeder was the only way to change the color without impacting real production. The additional material added at the feeder was a cobalt frit, small pieces of intensely colored glass about the size of pea gravel. The stirrers, though, were not turned on. The result was that a steady line of cobalt ran down the feeder, and each insulator produced had a portion of cobalt material in addition to the clear glass. Calvin stated that he had intended to create solid cobalt insulators, but the mixers were left off and so the cobalt frit and the clear glass were not mixed together properly. It is possible that the workers forgot to turn the mixers on. However, especially given the prior existence of the cobalt splotch mason jars made in 1968 for Kerr's 65th anniversary, it is also possible that the workers left the stirrers off on purpose, intending to create a similar effect.

Insulators produced later in the run had only cobalt wisps, as the workers had to make sure there were no signs of cobalt left when real production resumed. In all, between 125 and 150 cobalt splotches were probably produced. Don was given 2 cartons of the cobalt splotches, which probably each held 50 insulators in 2 layers of 25. Not all the splotches made were given to Don -- perhaps 2-3 dozen were smuggled off the annealing lehr by others. Some of these have shown up at various times -- there are reports of these insulators being found at flea markets, in Western Kentucky, for example. There is a report of one being found on a working line in Tennessee. The vice president of the Kerr Glass Company in charge of their Santa Ana plant even gave away 3 of these cobalt splotch insulators in late 1972, to an early collector, along with a complete set of their line of insulators at the time.

Shortly after the cobalt splotch insulators were made, Don Wentzel and his son Richard took them to an August 6, 1972 insulator show in Bergenfield, NJ. Calvin went to the show with them, and brought along an example that had broken during annealing, in order to show that the cobalt color was actually in the insulator rather than a surface coloring. They offered the insulators for $5, but no one was interested. The cartons of these insulators went back with Don Wentzel, and were stored in his basement.

Fast forward almost 10 years, to the NIA National Show in Rochester, NY. Don and Richard Wentzel brought a significant number of cobalt splotches to the show, probably half a table of them, and sold them for $5 each. At the time, most of the veteran collectors said they thought they would stay at $5 forever, since they were of recent production and "not really an insulator". Many seemed to feel that they were in the same category as the NIA commemoratives. But they sold well, and this is where they appear to have first become widely distributed in the hobby. Some people bought a number of them, and subsequently sold them at other shows. At the Genesee Valley Bottle Collectors Association Show and Sale a year later in 1984, for example, a dealer sold at least one for $20. The price increased significantly as their popularity increased greatly over the years. Today, these are valued at $700-800.

In 2009, as a tribute to his late father Don, Richard Wentzel had Wilkerson Glass produce a miniature version of the much sought after cobalt splotch Kerr DP1.


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