Magic about moulds

With special thanks to Adam Dodds for his unique account and photo of the Sowerby factory.

It's fascinating to study the mould or plunger that made a piece of glass and to see the pattern cut in reverse.  Sometimes the design is  cut in to the metal so that the pattern comes out in cameo (raised up off the surface) on the glass - as in the case of both the "Woodsland Pine" and "Flowers of the World". Other times, the design is left proud on the surface of the mould, and the areas around the main pattern are cut away on the metal - this results in the pattern on the finished glass being intaglio (incised into the glass) sometimes described as "near cut".

Below we show some more metal work and the glass produced - plus a special section from Adam Dodds, who worked at Sowerby's during the late 1940s and early 1950s.

Adam Dodds worked at Sowerby's during the late 1940s and early 1950s as their Glass Technologist. He kindly gave us his comments on what he recalls about mould making at the factory during that era.

Adam Dodds: "In the absence of a copying machine (the pantograph), at the stage where the Fentons mould maker rough cuts the pattern on iron (as seen here for the Woodsland wwwcga mould) our mould makers at Sowerby's had to do the same thing directly on to the cast iron mould for the entire pattern, using the same sort of hand tools which Fenton now uses for finishing off. Also, at Sowerby's we did not have those early stages of wax casts and plaster moulds that Fenton have now. Our mould components were made of chill cast grey cast iron, cast in sand moulds (in our own one man foundry). There was no detail whatever and every surface was rough.  The approximate shape and size would be determined from whatever model or drawing had been provided.

A great deal of machining took place of every surface other than what was to become the outside of the mould which would never contact glass or other bits of the mould.  Milling, turning, shaping, drilling, reaming and hand fitting were involved. Only after all this would the mould cutter (as such - he may well have done a lot of the machining in earlier days) be involved.  The virginal surface to be cut was lightly copper-coated and the intended pattern would be accurately marked in pen and ink. That might involve geometry (eg star bottoms) or pure art. Modelling clay played a big part both to check progress ("take a clay") or possibly to take an impression from whatever model might be available. Hammer, chisel, riffler files and emery cloth were the only tools."

What Adam describes above is, of course, how it was done during the Classic Carnival era too. The Hipkins Mould Company (who made many of the Carnival Glass moulds and plungers) and others, would have used the techniques much as Adam describes above.

So the next time you look at a piece of glass and marvel at its intricate and lovely design - spare a moment to thank the mould makers too.