Bone China Thimble
| Although one method of bone china thimble making is no longer done, slip-casting is still used today to create decorative thimbles. With multiple firings and layers of glaze to be applied, bone china thimble making is still an intense process. |
Thimbles
Bone china thimbles, which are as, if not more decorative than they are functional, came into their own in the mid 1800s. Made of clay and fired multiple times to achieve the final shape before hand-painted designs were added, there were two methods for creating the basic form. In both forms the thimble started out as cake clay which is shipped to a thimble factory in slabs where it was mixed with water and other materials such as silica until a precise balance was reached. This is called the slip form.
In the original bone china thimble-making process, pottery had just exited the stage where everything had to be shaped by hand. The invention of the jolley for the casting of hollowed-out shapes made the creation of basically standard-sized thimbles possible and removed some of the skill requirements inherent in crafting such small designs. At this stage, the slip forms were put through the jolley and molded to the desired shape and size. When a piece was satisfactory, it was then dried and fired. At this time firing was generally done in an oven which took a great deal of time.
The second process for creating the basic thimble form in bone china was developed a bit later and, called slip-casting, is still in use today. In slip-casting, the clay mixture is poured into casts. Different materials can be used for these casts, absorbent material being more useful for soaking up the excess slip. The longer the thimble was kept in the cast, the more slip dried and the thicker the thimble would be when finished. After casting, the thimbles were put on specially-shaped molds for firing. By this point in time kilns were much more common and could fire clay far more quickly than ovens could in previous years. After the first firing, both processes follow the same steps. An underglaze is applied; this would be the background color or parts of a decoration that require a particularly high heat to fuse. For example, cobalt blue requires a much higher temperature than normal glaze. When the thimbles come out of the kiln after the underglazing, another layer of glaze is applied, this time with decoration.
Sometimes, for the finest products, after firing the last layer of decorative glaze in place, a clear layer of glaze is applied and a fourth firing is done. Firings with glaze are called glost firings and, particularly with less technologically-advanced kilns, required that special care be taken lest the glazes discolor when they come in contact with certain fumes. After firing there is no way to recover a thimble if a mistake occurs so at this point a lost thimble is simply wasted time and effort. The last stage includes any special designs or additions, for example adding a ring of gold or silver enameling or an artist’s painting. At this point, both now and in the past the thimble is a finished product ready for sale.