The term “stoneware” is generally applied to pottery which has withstood a high oven temperature to such a degree (1200-1400 centigrade) that the body has vetrified and become impervious to liquids.This ware was known as "saltglaze" because of the way it was glazed. They threw salt into the kilns at high fire, the end result of which was a pot that came out with a sheen along with a texture much like an orange peel, really quite lovely.
The most beautiful and the rarest is what is called "drabware" it is darker than the white saltglaze but it is much more delicate and harder to find since it was only in production from the 1720s through the 1730s. The use of applied relief on this ware is some of the finest you'll see. "The Elers Brothers are credited for bringing this technique to North Staffordshire."
A side note about sprigging and applied relief:
"...the stems were made by applying thin, hand extruded strips of clay while the leaves and fruit were mold-made. Later, relief patterns were made by a process called 'sprigging': instead of being stamped on the surface, the reliefs were made in separate plaster-of-Paris molds, removed from the molds, and then by means of a slip (called "luting" or "vineing") were applied to the vessel." As you browse through the site, you will see an example of a pot with this type of intricate decoration.
Source: "The Burnap Collection of English Pottery by Russ Taggart"
The pot pictured here is of a whiter clay base made from a ground calcinated flint and devonshire clay. These were a combination of clays of Dorset and Devon which were what transitioned the Saltglaze market from the drabware color to a whiter saltglaze.
This article is heavily quoted from Arnold Mountford's Book, "Saltglazed Stoneware", a book I would highly recommend to anyone who is interested in this subject.