Dating design pattern
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.While technically a trademark, it is most often seen referred to as a backstamp. The configuration of the backstamp would undergo a few revisions after the introduction of opal glass kitchenware in 1945. A listing of patterns by year of introduction can be found .
Clear glass #500 series refrigerator storage dishes were made both in the late 1940s and in the early 1980s.Side by side comparisons, however, are often necessary to distinguish among them.From the time of introduction, the #400 nesting mixing bowl set was offered only as a set and in the original colors.The #063 oval divided dishes made before the mid-1970s were not marked with a model number.All Pyrex color ware was discontinued after about 1986.After 1959, the top surfaces were smooth and the undersides were fluted lengthwise.
#500 dishes sold in 1957 and after in any color or patterns, therefore, should have the later style lids.
The design of #500 series refrigerator storage dishes' lids can help determine their age.
From 1947 until approximately 1959, the lids' tops had longitudinal ridges flanking a smooth middle, and had smooth undersides.
For each product, the list contains a sorted list of the providers that have that particular product.
In that way, we can order certain products from whoever happens to offer the best price.
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.