about centrifuged glass

In the 1940ies some people started to experiment with the centrifuging of glass, as a technique to manufacture thicker bowls. One of the anecdotes often told is that NN saw someone using a butter churn and started to think.
A more plausible story is that NN saw a milk separator...

So, who was NN, who was the first?

A common opinion says it was Sven Palmqvist at Orrefors, another says it was Magni Magnusson at Skruf. The idea might have been "in the air", but fact is that Palmqvist was given both a Swedish and an American patent.

According to the book Sven Palmqvist - glaskonstnär (ISBN 9188 712 86 9) the first patent application was filed in 1943, for a "device to manufacture glass objects".
This device was rather primitive: hand operated, with a removable mould which had to be detached to tip out the centrifuged object.
One problem with the first centrifuge was that it did not have a stop collar at the top - the book mentions (my translation): "The molten glass could, at high speed, escape over the top of the mould, thus burning the pants of the operator".
Another patent application was filed in 1946, now for a bettered device: it now had a collar, and was also powered with an electric motor.
At this point Magni Magnusson intervened: he had filed an application in 1941 for something similar. In 1951, the case was resolved, and the Swedish patent no 133629 was awarded to Palmqvist (see link above).

The centrifuge was further developed - first the material of the moulds (to reduce the need of further processing), later the moulds got an ejector at the bottom to facilitate removal of the objects.

The technique was not loved, to begin with. It did not take off until the manager at NK (famous store in Stockholm) declared they wanted the centrifuged bowls as part of their "Swedish grace" goods - in 1954 Orrefors started manufacturing the series "Fuga", and it was an immediate success.

Later, the technique was adopted by several glassworks, but it can be said that Orrefors was the leading company.

We show several examples of the technique - some Fuga bowls, but also a couple of more "advanced" objects. Lars Hellsten is one of the designers who has worked extensively with the technique for Orrefors.

As said above, it is Orrefors who has specialized in "perfect" results.

Many centrifuged objects from many other glassworks one can often see the same defect: the surface gets ridges (see picture: a close-up of a drinking glass from the service Mine from KostaBoda).

Nobody has found a good explanation, but it probably has to do with uneven temperature of the mould.

Below a short video showing centrifuging at Bergdala in the spring of 2017.

Sources:

Palmqvist & Rudström: Sven Palmqvist – glaskonstnär, Stockholm 2006, ISBN 91-88712-86-9
personal communication: Hans Karlsson, Hovmantorp 2015

Many people do not think it "good English" to use centrifuge as a verb. However, professor Keith Cummings uses it as such, in the book A history of glassforming, ISBN 0-7136-5274-8, from 2002 - so I consider myself being in good company.

på svenska För andra språk erbjuder vi/ for other languages we offer Start page for the museum About us Machines and artifacts in our museum About the building Glass as a material, and the glass industry About hot glass techniques - Glass melting furnaces - Glass pots - Pressing, a general descripion - Swedish pressed glass - "Baking pancakes" - Centrifuging - Vacuum flasks About cold glass techniques Links Literature list Downloads, catalogues (opens in new window) museibloggen (written in Swedish) Facebook group for the Museum Contact us How to find us More about Bergdala		Centrifuging glass In the 1940ies some people started to experiment with the centrifuging of glass, as a technique to manufacture thicker bowls. One of the anecdotes often told is that NN saw someone using a butter churn and started to think. A more plausible story is that NN saw a milk separator... So, who was NN, who was the first? A common opinion says it was Sven Palmqvist at Orrefors, another says it was Magni Magnusson at Skruf. The idea might have been "in the air", but fact is that Palmqvist was given both a Swedish and an American patent. According to the book *Sven Palmqvist - glaskonstnär* (ISBN 9188 712 86 9) the first patent application was filed in 1943, for a "device to manufacture glass objects". This device was rather primitive: hand operated, with a removable mould which had to be detached to tip out the centrifuged object. One problem with the first centrifuge was that it did not have a stop collar at the top - the book mentions (my translation): "The molten glass could, at high speed, escape over the top of the mould, thus burning the pants of the operator". Another patent application was filed in 1946, now for a bettered device: it now had a collar, and was also powered with an electric motor. At this point Magni Magnusson intervened: he had filed an application in 1941 for something similar. In 1951, the case was resolved, and the Swedish patent no 133629 was awarded to Palmqvist (see link above). The centrifuge was further developed - first the material of the moulds (to reduce the need of further processing), later the moulds got an ejector at the bottom to facilitate removal of the objects.
		The technique was not loved, to begin with. It did not take off until the manager at NK (famous store in Stockholm) declared they wanted the centrifuged bowls as part of their "Swedish grace" goods - in 1954 Orrefors started manufacturing the series "Fuga", and it was an immediate success. Later, the technique was adopted by several glassworks, but it can be said that Orrefors was the leading company. We show several examples of the technique - some Fuga bowls, but also a couple of more "advanced" objects. Lars Hellsten is one of the designers who has worked extensively with the technique for Orrefors.

		As said above, it is Orrefors who has specialized in "perfect" results. Many centrifuged objects from many other glassworks one can often see the same defect: the surface gets ridges (see picture: a close-up of a drinking glass from the service Mine from KostaBoda). Nobody has found a good explanation, but it probably has to do with uneven temperature of the mould.
		Below a short video showing centrifuging at Bergdala in the spring of 2017.
		Sources: Palmqvist & Rudström: Sven Palmqvist – glaskonstnär, Stockholm 2006, ISBN 91-88712-86-9 personal communication: Hans Karlsson, Hovmantorp 2015 Many people do not think it "good English" to use centrifuge as a verb. However, professor Keith Cummings uses it as such, in the book *A history of glassforming*, ISBN 0-7136-5274-8, from 2002 - so I consider myself being in good company.