Pyrex pattern dating
Unfortunately to everyone but myself, I have fallen in love with this pattern and will not sell this set for any price. This collection is just too special for me to part with it.
Side by side comparisons, however, are often necessary to distinguish among them. A revised backstamp, with PATENTED above PYREX and MAY 27, 1919 below, was used after that date through 1924. A model number and, later, the capacity in pints or quarts were added above, and OVEN WARE below. Later pieces are also recognizable by, instead of "MADE IN U. A.", the the wording "by CORNING, Corning, NY, USA" with the verbiage NO BROILER OR STOVETOP or, later, BAKING AND MICROWAVE below. Starting in the mid-1970s, equivalent metric capacities were also embossed on pieces, therefore any seen so-marked can be dated positively later than that.While colors and styles of decoration reflected consumer tastes at the time of production, the first thing to look at is the backstamp. But the product would not be branded Pyrex until the debut of kitchenware made from it nearly a decade later. New patterns were introduced in keeping with changing tastes, so they can also give clues as to time period.Backstamps On the bottom of most every genuine Pyrex opalware article is an embossed set of markings which contains a variety of information. The backstamp seen on various items prior to that echoes a Mac Beth-Evans trademark, but one not previously used on their glassware: that of a glassblower, or "gaffer", nicknamed "Little Joe". Since pattern collections and promotional pieces were available for relatively finite periods, knowing their years of introduction and discontinuance can also help narrow down dating somewhat.