There are many ways to make colourful patterns on porcelain china these days. Some are easy for anyone to use, like decoupage, waterslide decals, and air-dry paints like Delta Air-Dry PermEnamel.
Others, like dye sublimation printing, transfer printing, and hand-glazing high-fired pottery, require a lot of money for equipment and work best for businesses with a lot of money or artist cooperatives.
Hand-painting and transfer printing are still two of the most common ways to put designs on porcelain. A high-tech version of waterslide decals is used in the business world. It involves screen-printing decals with glazes and putting them on porcelain. Before decorating, the pottery is high-fired to at least cone 6 in each case. [Cone is a way to measure how much heat something has taken in after being heated over time. Depending on how quickly the kiln heats up, Cone 6 is between 2165 and 2269 degrees Fahrenheit. Real porcelain is hard and almost see-through because it is fired at such a high temperature. The piece is then decorated, and the glazes are melted and fused to the porcelain by firing it lightly several times.
As new techniques have been made, the word "porcelain" has come to mean more and more things. If you ask a potter to explain what "porcelain" means, he will probably use the standard definition. A potter thinks that real porcelain is white clay that has been fired to cone 6 or higher and is at least a little bit see-through. It has a lot of kaolin clay, and the rest is mostly made up of feldspar and silica. This mix of clay is what gives porcelain its pure white shine.
Porcelain comes in three grades: hard-paste, soft-paste, and bone china. Artists who paint on porcelain but don't make it themselves call them hard-paste, soft-paste, and bone china. They all have kaolin, but only the hard-paste is high-fired and has feldspar and silica. The body and glaze join together because of the high temperatures. When a piece of hard-paste porcelain breaks, you can't tell the body from the glaze.
Soft-paste porcelain is made by adding ground glass or frit, which is material for glass that has not yet fused and hardened (1999 to 2109 degrees F). Because soft-paste porcelain is fired at lower temperatures, it does not completely vitrify and stays slightly porous. When soft-paste porcelain is broken, you can see that it has a grainy body and a layer of glaze that is smooth and shiny.
Bone china is made by adding bone ash to kaolin, and it turns into glass between cone 2 and cone 5. (2034 to 2205 F). Bone china is more durable than soft-paste porcelain, even though it is not as hard as real porcelain. The bone ash makes the porcelain a lot more see-through.
Lastly, go to a store that sells tiles and look at the "porcelain" tiles there. If you turn them over, you'll see white, brown, or grey clay at the bottom. In the tile business, "porcelain" has nothing to do with the amount of clay or the level of firing. Instead, tile makers call a tile "porcelain" if it has been fired to the point where it absorbs less than 3% of water.
