Percival Marson - glass chemist
We owe a debt of gratitude to the glass chemist, Percival Marson, for the use of iridescence on glass in England.
According to Cottle, “Sowerby: Gateshead Glass”, Marson was the “original Stourbridge developer” of iridised glass, going on to be a chemist at Sowerby’s on Tyneside. Cottle explains that Marson first developed iridescent glass at Sowerby’s in 1905, but it didn’t work out too well. Fortunately for us Marson persisted and in the early 1920s (in his position as Sowerby’s chief chemist) he got it right: “his Straw Ruby colour went into production as Sunglow and Rainbo lustre”.
Sunglow was Sowerby’s marigold iridescence on clear (and also rarely on vaseline) base glass.
Rainbo was the darker iridescence found on amethyst, blue, black etc., glass.
Marson penned an interesting little book called, simply, “Glass” (or to give it its much longer and fuller title: “Pitman’s Common Commodities and Industries – Glass and Glass Manufacture by Percival Marson, Consultant upon Refractory Materials etc., Honours and Medallist in Glass Manufacture”). In amongst all the technical detail is this interesting snippet:
“Iridescence can be formed by re-heating crystal glassware within a chamber in which salts of tin, barium, aluminium, and strontium are volatilised. This method produces a superficial (that is a surface) iridescence.”
Marson certainly knew his stuff and clearly without him Sowerby’s wouldn’t have made their fabulous Carnival Glass.
Thanks to Percival Marson, chief chemist at Sowerby in the early 1920s, they had the technical know-how to produce beautiful iridescence on items such as those shown above. On the left, a marigold Diving Dolphins rosebowl; on the right, a marigold Covered Swan; at the back, a black amethyst Sowerby Drape vase and in the foreground, an amethyst Royal Swans posy.