From my regular series of Design Icons written for ABC RN Blueprint. You can find others on my main page and also on the Blueprint and Podcasts pages.

Pyrex measuring jug was broadcast on the 26th February 2022. You can listen to the audio here.

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Who would have thought that railway safety would lead to a measuring jug, an item as common in kitchens as a wooden spoon? But that’s the story of Pyrex.

When the brand was launched in 1915, its selling point was that it wouldn’t scratch or break, even when placed in a hot oven. The range of ovenware included a large dish in which to bake a pie, that American staple. The measuring jug arrived some years later with raised mouldings in the glass to show fluid measurements. That changed in the late 1930s to the red lines and numbers that we know today. While the Pyrex name might sound vaguely Greek or Latin, it is in fact a play on the word pie combined with the brand name Nonex, the glassware that led straight to Pyrex.

Nonex was an exceptional glass developed by the Corning Glass Works for railway signalling lamps, whose glass casings were subject to punishing temperatures, with potentially disastrous results.  It was the American version of borosilicate glass, invented in 1893 by a young German chemist called Otto Schott and given the name Duran in Germany. It was made using a high proportion of silica and boron oxide which meant it wouldn’t expand or contract in extreme heat or cold. Its low conductivity made it perfect for battery casings.  It was in Germany that Eugene Sullivan first encountered it and when he became head of research at Corning, he thought they could make their own version.

From that came Pyrex. The story goes that it was the result of a happy accident, when the wife of research physicist Jesse Littleton baked a cake in a cut-down battery casing made from Nonex. The truth, however, is that Littleton wanted to test whether the glass could conduct heat evenly enough to make it useful in the domestic kitchen. The cake was a success and so the laboratory set about refining the glass, removing the lead but maintaining the critical ingredients of boron oxide and silica. From its launch it was an immediate success, seen almost as a miracle material.

There was a cheaper alternative, which was not quite so resilient but judged good enough. Ordinary soda-lime glass, used for everything from window panes to bottles, could be strengthened and made heat resistant by rapidly heating and cooling it. This was used by Duralex in France for their famous bistro glasses of 1927 and Pyrex started to use it from the late 1930s in a new range of baking dishes, the glass now in an opaque colour. It proved to be the perfect background for applied decorations, and jaunty floral or geometric designs have made them treasured symbols of mid-century-modern style. Naturally the measuring jug remained clear, with those made in tempered glass having a bluish tinge compared to the colourless borosilicate glass versions. The jug’s design has barely changed, although it now has an open handle so that several can be stacked together.

Borosilicate glass remains vital for laboratory glassware, valued for its thermal qualities as well as its ability to cope with harsh chemicals. So whenever you’re measuring something in your Pyrex jug, know that you’re tapping into a history of science and safe railway travel. And you can’t say that about a wooden spoon.