One is not likely to find English Yellow-Glaze with any frequency, unless you attend a show where the same quality dealers are there each time and one of them is specializing in English Yellow Glaze, as I have long done.
About twenty-five years ago, Mr. and Mrs. Jack L. Leon gave about six hundred examples to the Smithsonian Institution, which they had assembled in a relatively short time. After Jack Leon's death, Mrs. Leon continued to collect.
Basically Yellow Glaze is pottery and two very refined types of pottery. First called Creamware, about 1770, blueing was put into the glaze and then it was called Pearlware. To learn this shocks some because they are accustomed to thinking that both those types of pottery are cream or white and they are.
Something radical was done, a yellow overglaze was added before the many types of decoration were added, making what J. Jefferson Miller II, in his 1974 book called English Yellow-Glazed Earthenware. So Yellow Glaze, like so many wares of the late l8th and early19th centuries, is on either Creamware or Pearlware, as is Gaudy Dutch, another well known type of pottery from the same period.
If you have been collecting Yellow Glaze, or if you want to begin to acquire the best pieces, it would be best for you to find a dealer among whose special types of pottery is Yellow Glaze. If your thrill is in the hunt, then going from show to show may fill your thirst but is not likely to add much to at the satisfaction of adding fine examples to your collection.
The main reason you may not have seen Yellow Glaze before is that developing yellow glazes and keeping them yellow under high firing temperatures caused problems, for centuries. There is little yellow early 18th century Meissen or later in the century, Worcester, both fine porcelain, as opposed to pottery.
Considering how little of this ware came on the market in the last thirty five years, the price is still very moderate. For example, the price of the average Mocha Ware mug has increased about 9 times, and Blue Spongeware 20 times in this period. Yellow Glaze has increased only a fraction by comparison.
Today, most examples of Yellow Glaze are between about $1200-2500. A Spongeware custard cup that was $18 twenty five years ago, is now $250-300, for example. (Yellow Glazed Earthenware by Rufus Foshee, Specialist in 17th, 18th, and 19th centuries pottery and porcelain.