What is the difference between Stoneware, Earthenware, and Redware? The correct answer is they are all technically earthenware, but that is not especially helpful.
Donald Webster said it best. “All earthenware pottery except stoneware is unvitrified. That is, the clay particles are not fused together by silica and the fired pottery is porous to liquids if not glazed. Stoneware or porcelain clay, conversely, has a higher silica content than most earthenwares, is fired at a much higher temperature, and even unglazed stoneware or porcelain is vitrified and non-porous.”
The higher firing temperature of stoneware allowed for a superior glazing process. When the kiln was red-hot, salt was shovelled in. The salt vaporized and fused with the clay, covering the outside in a clear glass-like glaze. Hence the term “salt-glazed stoneware”. Simply put, stoneware was a better product, less likely to leak and considerably more durable than other “coarse” earthenwares.
Stoneware clay typically fired a grey or buff colour, and the salt-glaze was transparent. This made a great canvass for decorating in cobalt blue slip.
The Eberhart & Halm (Toronto) jug in fig 1 is a beautiful example of decorated Canadian stoneware.
Note that sometimes stoneware will have a reddish tone, which can be confusing to collectors. This colour may be the result of the composition of the clay or the result of firing.
The Brantford Potteries miniature stoneware churn in fig 2 has an unglazed base with a distinctly red colour.
In 19th century Canada, virtually all the stoneware clay was imported from the States or England. Importation was necessary as there were no significant sources of stoneware clay known in the country at the time. Only a handful of larger industrial potteries could afford the expense of importing the clay.
Small and mid-sized potteries ran on tight budgets. To keep costs low, they relied on clays found cheap locally. Objects made from these local clays were air-dried or fired once, then dipped in a liquid glaze mixture, and fired to a finished product.
The glaze mixtures were highly variable, resulting in a multitude of colours and textures. Pottery made in this fashion is commonly referred to as earthenware.
Depending on the source of the clay, earthenwares would fire a buff (white, beige or light brown) or red colour.
Fig 3 shows an impressive buff earthenware pitcher made by Adam Bierenstihl (Waterloo).
Fig 4 shows a red earthenware jug with a terrific glaze made by John Kulp (Grimsby).
Red earthenware is commonly referred to as redware for short.
Many earthenware potters went out of their way to imitate the better quality (and therefore more desirable) stoneware. Fig 5 shows a buff earthenware jar made by the Huron Pottery (Egmondville). To complete the illusion, the jar is glazed in a cream colour with blue slip decoration.
If you are just starting out collecting antique Canadian pottery, you might find it challenging to tell the difference between stoneware and earthenware at first, but it gets easier the more of it you handle.
Interestingly, collectors tend to prefer one or the other, and I know few people who actively collect both. Personally, I prefer the individuality and the bold glazes of earthenwares.