Jiggering is the mechanized counterpart of the potter's wheel. In jiggering, a plaster mould is spun at speeds of about 200rpm in a cast iron head. The jiggerman places very soft clay in the mould and brings down a tapered profile attached to a rigid swinging arm. This forces the clay to assume the shape of the containing plaster mould on the bottom and the contour of the template on the top. Over a few hours the plaster mould draws water from the clay and the clay hardens, shrinks, and pulls away from the mould. The piece can then be extracted and the mould used again.
The heavy automation of pottery manufacture is thus a relatively recent development. Companies in Medicine Hat were on the cutting edge of adopting this technology by the early 1900s. Local companies perfected the jiggering process and developed custom equipment and techniques, some of which were patented. They were able to overcome considerable technical challenges and successfully produced very large crocks and other vessel shapes.
Jiggermen were paid by the piece. From this money they paid 'runners' who made sure they had moulds and clay always at hand and that ware was properly stacked. The catch was that the jiggerman was only paid for pieces making it through the kiln without defect. A good team could make several thousand pieces a day. The "Age of Efficiency" had come to an isolated farming town on the Canadian prairies and people had to adapt. People typically worked 6-day-weeks. Every job in the plant had to be done properly; one person's poor workmanship could affect the income of many others in the plant.
The large box structure called the ' mangle dryer' was used to speed up the drying process and keep the moulds from becoming saturated with water. You can see it against the south wall. This drier used waste heat from the kilns and was efficient enough to enable cycling the moulds many times each day.
Since clays shrink during drying, it was important that ware be dried evenly to avoid cracking, especially during the 'leather hard' state just after being removed from the moulds. These ware racks had to be kept in a hot, damp, draft free environment. The plant as a whole had this type of atmosphere. While this did not make it pleasant for the workers it helped to assure trouble-free drying.
As a volunteer, Basil Leismeister makes all of our jiggered ware that is on sale in the gift shop and also gives demonstrations. The large jigger machine that Basil uses for making crocks and bowls was used in the 1920s and was originally installed at Medalta Potteries.
7. Plaster is one of the key ingredients of ceramic manufacture to this
day.
Each of the potteries would have used many tons of plaster each month
to make moulds to replace those that were wearing out. Plaster is so useful
in ceramic manufacture because it is both rigid and very absorbent yet
easy to mix and pour into any shape. This
means that not only does clay not stick to it, but it draws water from
the clay.
