This is an unusual gray-area insulator: it's not quite "factory" but it's also not "fake". It was made in 1972 at the Kerr plant by factory employees on factory equipment with the blessing of the company, but it's not a production insulator. The story is that the employees had intended to produce a pure cobalt insulator, but oops, they forgot to turn on the stirrer! However, Kerr had previously produced cobalt splotch commemorative Mason jars in 1968, so the splotches may have have been by design.

Richard Wentzel, Millville glass expert, says "The cobalt was hand introduced into the feeder. It was crushed cobalt glass. The mechanism which would have stirred it properly into the glass stream did not get turned on, so instead of a solid cobalt colored CD 155, you got just a splotch" (where the little pieces of frit moved in the glass while the glob was processed into an insulator).

The color chips looks like concentrated frit to me instead of pieces of cobalt cullet: they are black, and leave rich cobalt streaks in their wake. If they were pieces of cobalt glass, they would be cobalt colored, not opaque black.

It is believed that from 100 to 150 were made. They are very popular today and sell in the $750 to $1,000 area. When first made, they were brought to an insulator show and offered for $5 but there was little interest at the time.

While cobalt is always an attractive color and they would have been welcome in pure cobalt, I find the streaky version ever better: each one is unique! And talk about contrast!

You can read more about this piece in "History of the CD 155 KERR DP1 Cobalt Splotch" here: <http://www.insulators.info/wiki/History_of_the_CD_155_KERR_DP1_Cobalt_Splotch>