We’ve had these interesting older mugs for quite awhile now, but only got around to posting them now. For one we weren’t too sure about their history - we know the cup on the right is known as a Military Handwarmer Watch Mug and have been dated back to the World War II era when they were created to be used by soldiers and military staff. These are EXTREMELY heavy duty mugs (they have the thickest walls of any Pyrex item I’ve ever seen) and were meant to stand up to everyday use in military kitchens and in the field.
We have seen some conflicting statements that they were actually produced and used in the Korean War as well or even later, but we are not sure about that - or whether it is possible to exactly date them. Like a lot of Corning and Pyrex, it is sometimes possible to get a fix on when an item was FIRST released - however it is another to figure out when an actual piece was made. This is especially problematic because many Pyrex items were in use for decades with little change. One thing we are fairly certain is that later colored opal kitchenware and tableware came about as a direct result of the research done by Corning on glass breakage.
The mug on the left is interesting because it is very similar in shape to a #723 Tableware mug, but it seems to be made in the same fashion as the Handleless Watch Mug. The color is a similar off-white, almost yellowish shade - not as dark as the Watch Mug, but darker than normal. We wonder if perhaps this mug was some sort of interim stage between the release of the #723. It is marked on the bottom with the Corning Glassblower stamp - the same one that is on the Watch Mug.
Interestingly, the handles are slightly different as far as we could tell. Below is a shot of a Blue Band Tableware #723 on the left, and the Corning mug in question on the right. The handle “loop” is slightly different in shape:
It is interesting to compare the wall widths of the mugs. While it is not always possible to date a Pyrex item by the thickness of the glass, it is often a good indication that an item may be a bit older if the glass is thicker. (This is not always true, though)
Here is a example comparison of wall widths. Counterclockwise from the top right: The thickest wall is by far the Handleless Watch Mug. Next thickest is the Interim #723 mug with the Glassblower logo. Finally, quite a bit thinner is a standard diagonal handle Old Town Blue Mug.
We are going to wait to enter the Corning Watch Mug and the #723 style Corning Mug into the reference for the time being. We would like to compare them with a few other items, and perhaps other people might have more information on it. (By the way, there is an advertisement for the Watch Mug in Rogove and Steinhauers Pyrex By Corning book, page 23)