History:
In the year 1813, Charles Mason patents his formula for an extremely durable earthenware. This vitreous pottery is made from a combination of clay, iron slag, feldspar and a small bit of cobalt. Ironstone ware, more commonly known simply as ironstone, is porous and 
glazed. While typically classified as earthenware, ironstone is more similar to high quality stoneware. Ironstone looks similar to porcelain however it is opaque where porcelain is translucent.
Mr. Mason would decorate his ironstone pieces with transfer patterns before glazing in the style of porcelain china (transferware). The transferware sells well in England in the early 1800’s but in the United States, the simple, plain white pieces are preferred. By the 1840’s large amounts of white ironstone is being exported to the American and the Canadian markets. In fact, very little “white” ironstone stays in England, the majority of it is exported.
Originally, English potters give names to ironstone like graniteware, stoneware, pearl china, feldspar, semi-porcelain, opaque porcelain, English porcelain, stone china and new stone. All of which are now categorized as ironstone. The earliest pieces of ironstone have a bluish tint to them. Later pieces have the creamy white color. According to avid ironstone collector, Martha Stewart, in addition to the potter’s marks, you can date ironstone pieces by their shape.
Dating:
- 1830’s to 1840’s: referred to as gothic or primary – consists of paneled, hexagonal or octagonal shapes
- 1850’s: leaf patterns are popular
- 1860’s: round shapes
- 1860’s to 1880’s: highly decorative patterns – harvest patterns with berries and sheaves of wheat, bulbous patterns with ribs of leaves and flowers
- After 1880’s: patterns return to simpler forms
Avoid pieces like this that have pitted. The crack has gone deep beneath the glaze into the pottery itself.
What to look for:
- Quality is based on the eveness of color and the relief work.
- Pieces should be chip-free and sure handled.
- Finials should have no evidence of repair.
Cost:
You can pick up ironstone pieces for just a few dollars or few a few hundred dollars. The cost of ironstone pieces will of course depend on the quality of the piece but will also rely on the following factors:
- the maker
- the pattern
- the rarity of the piece
Crazing:
Crazing happens when a piece of pottery or ceramic gets fine, minute hairline cracks in the glaze. These cracks, however, rarely effect the clay itself. Crazing can indicate the age of a piece. A newer piece would only have crazing if it is poorly made to start with and there will always be other indicators of poor quality. If you run your fingers over the crazing, you should not be able to feel the cracks.
Crazing is very common and while a piece with no crackling at all is optimum, crazing will not necessarily affect the value of the piece. Normal amounts that can’t be seen from a few feet is fine.
Marks:
The mark is the potter’s or the manufacturer’s hallmark. It is typically placed on the bottom or the side of a piece. Not all ironstone will bear a mark. How the hallmark looks and how much information it will give you depends upon the mark and when it was made. It may include the maker’s name and location, initials or even the name of the hotel or restaurant it was made for.
How can you tell if it is ironstone if there is no mark? Typically by the weight of the piece and it has a bit of a luster to it. The color itself can be bright white or dark cream. If you hold a piece by its handle and flick the body of the piece, it should produce a nice ping.
These are examples of potter’s marks on ironstone pieces.
