Description:Pottery factory interior depicting a dipper and his female assistant working in a dipping house.
The workers are in the process of dipping fired (or biscuit) ware in preparation for a second glost (or glazed) firing.
Taken at the Spode factory in Stoke-on-Trent in 1960.
Health risks associated with glaze.
Glaze consists of;
Silica.
A flux to lower the melting point of silica.
Alumina to stabilise the mixture.
The most commonly used flux was lead, which created serious health problems for the dippers.
Lead is absorbed through the skin, by inhaliation, or through the mouth.
It tended to be absorbed into the bones and affected the tendons. This caused "dropped wrist" and "dropped ankle".
Other symptoms of lead absorbtion included stomach disorders, miscarriages, anaemia, epilepsy and paralysis.
Many workers died of lead poisining (plumbism).
Women and children were at the greatest risk.
Why do it then?
Dipping was a well paid job.
People simply took a chance and hoped they would be lucky enough not to be affected.
To reduce the risks workers would take epsom salts and drink milk to line the stomach.
Manufacturing benefits of using lead in glaze.
Lead gave a brilliant white glaze.
Lead gave good even coverage without fingerprints.
Lead prevented crazing.
Alternatives were unfamiliar and expensive.
Factories did not share recipies, so each had to research their own.
Reducing the problem of lead absorbtion.
The solubilty of the lead in glaze was reduced by fusing it at high temperatures and grinding it. This was called
fritting.
Factories were encouraged and then forced by legislation into using fritted glaze.
Regulation and Legislation.
After 1st January 1899 all workshops had to be ventilated and cleaned at the end of the day.
In 1899 it was decreed that no more than 5% standard solubility of lead would be allowed in glazes.
A detailed set of rules was drawn up, which restricted the use of lead. After this date lead poisoning in workers began to decline.
In 1949 the use of all lead glazes which were not low solubility was prohibited. Since this year there have been no deaths from lead poisoning.
Taken from the Gladstone Pottery Museum Photographic Collection.
This photograph is part of the collections at Stoke-on-Trent Museums.