Glazing ceramic objects

Glazing provides ceramic objects with a thin layer of glassy coating. There are several reasons to glaze objects. It prevents water from being absorbed by the porous bisque when the object is used. It also provides it with an easy-to-clean surface. Finally, it can strengthen the object or give it a certain colour via the glazing. Several of these aspects are usually desired. Glaze is most similar to glass when it comes to structure and properties.

To get specific effects from the glaze, various metal oxides are added to it. Glaze is usually applied in one of two methods – dip glazing or spray glazing. At the factory, dip glazing was done until after World War II. Dip glazing involves dipping objects in a tub of glaze. The glaze is mixed with water in large vessels. The glazers at the factory held the objects in their hands and dipped them quickly. Then, an assistant took it from them and placed it on a table. When an object is dipped in glaze, the porous material absorbs the glaze at once. The glaze forms a thin film around the object. Dip glazing requires a highly developed work technique.

Hand movements had to be carefully adapted to suit the size and shape of an object. Fingerprints had to be avoided. For the glaze to gain the desired thickness, the glazers had to carefully monitor for how long the object was held in the glaze. If it was held in the glaze for too long, the layer became too thick, and if dipped too quickly, it would become too thin. This work technique had to be learnt through trial and error, and by seeing how others judged the glaze’s thickness on various objects. Coloured glazes were especially hard to work with, because the last drops of glaze had to be shaken off, so as not to create dark stripes or spots in the glazing.

At the factory, glazing was a job that required a well-coordinated team. The assistant had to keep constant watch on the glazer's movements , so that he took the dipped object from him at the right time.

26 people were employed in the glazing workshop, 12 men and 14 women. Work was paid by the hour up until 1935. From 1935 onwards, this was changed to piece rate pay. Experienced male workers earned from 100 to 107 Norwegian øre per hour. Male apprentices and women earned from 55 to 60 Norwegian øre per hour. Men glazed the heaviest objects. Women and apprentices took the glazed objects and placed them on a table. Women glazed lighter objects, such as cups and plates. During glazing, the glaze had to be constantly stirred to keep an even consistency. When items had been glazed, they were ready for glost firing.

Glost firing

In order to bind the glaze to the ceramic material, it needs to be fired at a high temperature. This process has a lot in common with bisque firing. Four kilns, with the same shape and construction as the bisque kilns, were used for glost firing. These were named Jon, Kristen, Håkon and Johannes.

Work with the kilns was done as piecework by a 34-person work team. Four of the 34 were women. The hourly pay was approximately 100 Norwegian øre for men and 55 to 60 Norwegian øre for women. As with the work team at the bisque kilns, the team shared various assignments among themselves. Following World War I, only three of the kilns were generally in use. Johannes, the smallest kiln, was from then on only used as a reserve, during especially busy periods or when any of the other kilns were undergoing repair. The work process was generally similar to the one at the bisque kilns. The items were placed in saggars and stacked inside the kiln. However, the process differed at one point, in that the items were placed on stilts. Stilts are little “feet” made of a ceramic material that prevented items from melting together during firing. When the kiln was fully stacked and sealed, the fire was started and the “burner” took over. There were two burners working shifts at the glost kilns. These kilns were fired at a slightly lower temperature than the bisque kilns. This was necessary to avoid tension forming between the ceramic material and the glaze. As with the bisque kilns, the firing could be monitored through inspection hatches. The burner climbed a ladder to study the flames and the positions of the pyrometric cones. Work as a burner could be dangerous. Firing in the glost kilns took as long as in the bisque kilns. When the kiln had cooled down, the finished items were transported on trolleys along tracks to the sorting cellar.


20 workers were employed in the sorting department – 4 men and 16 women. At first, work was paid by the hour. It became piece rate work in 1935, with an hourly rate that averaged 105 Norwegian øre for men and 55 Norwegian øre for women. The work was led by a male foreman.

In the sorting cellar, items were divided into three different categories: prima, secunda and kraks. Sorting was done through individual judgement, based on norms established by the management. Sorting demanded great skill and accuracy. It was necessary to be able to identify flaws quickly and to swiftly place the item in the right category.

After firing, the objects were left with marks in their glazing from the stilts. Any bumps were removed with a small steel spike and sanded. If the finished objects were not getting overglaze decoration, they were transported to the packing hall. There, they were packed for storage or shipment. Items to be given overglaze décor were transported on trolleys to the decorator’s workshop.


Goods were packed in wooden crates, protected by straw. This was done in the packing hall. There were 13 workers employed there, all men. The crates were nailed shut in a dedicated workshop, which employed four men. The packers collected the crates, in various sizes, when they needed them. From the packing hall, the crates were driven to a storage shed. The shed was located by the seashore. From the shed, the goods were loaded onto cutters or rowed to the steamship quay for shipping to buyers in Norway or abroad.

Another important group of workers were the cleaners. 6 women and 1 man were tasked with keeping the factory premises clean.

Any work involving clay is a potential health hazard. The clay is harmless as long as it is moist, but as soon as it dries, it forms tiny dust particles. If these particles are inhaled and wind up in the lungs, they will start to clog up the lungs. This results in breathing capacity gradually being reduced, making the person slowly suffocate. This is the infamous disease known as silicosis. Silicosis is incurable. When the damage has occurred, there is no way to heal it. Cleanliness and proper ventilation are the only ways to prevent silicosis.

Work at the factory was generally manual until the end of World War II. Most work operations required long training. The work was largely based on practical skills and gave workers a high degree of control over their own work efforts. This created workers that were conscious of their own professional skills.

It wasn’t like we thought we could outclass them. They were so confident in what they did, and so sure of their work. You couldn’t teach them anything. [translated]

The many clearly separated, dominating joints within the production line, makes the factory seem like a work-divided industrial company driven by strong craftsmanship.