Ceramics are usually formed from a raw mass at room temperature and obtain their typical material properties by a sintering process at high temperatures. Through the effect of heat (firing), earthenware then becomes “sintered ware”. In contrast, the term “ceramics” also includes glass, enamel, glass-ceramic and inorganic binders (cement, lime, plaster).
In the group of ceramics, the following types can be distinguished technically correct as follows:
Terracotta is a type of ceramic and it’s used to make many flower pots, bricks and sculptures. You may also hear the term “terracotta” to describe a color which is a natural brown-orange. It’s a very porous clay to work with, and a coat of glaze is needed to make it waterproof. It is the kind of ceramic fired at the lowest temperatures – some have fired it as low as 600ºC.
Earthenware is the earliest type of pottery and our favorite. Its slightly porous and coarser than stoneware and porcelain and its fired at temperatures typically around 1000-1080ºC. For practical and decorative reasons it is usually glazed, thus making it watertight.
Stoneware is fired at higher temperatures (usually 1150ºC-1300ºC) and because it is inherently non-porous the surface will be watertight. It can be left unglazed that it will still hold water inside. Stoneware is harder, stronger and more durable than earthenware and so is mostly preferred for everyday use, found normally in the kitchen since it can easily go into the oven and such.
Porcelain is fired at high temperatures – above 1320ºC – and like stoneware, its body vitrifies during the firing, so its surface is watertight naturally. The surface is very smooth and the most identifying trait of porcelain is its translucence. Porcelain after firing becomes very translucent, allowing light to show through it.
Low-Fired Ceramic (650 – 1,190 °C)
Fired Ceramic (1,200 – 1,290 °C)
- Durable China
- Diamond China
- Dynamite China
- China Fine
- China High
- Ivory China
- Bone china
- Soft Porcelain
- Viterous Porcelain
- Viterous China
- Viterous Chinaware
Porcelain – Highly Fired Ceramics (1,320 – 1,450 °C)
- Feldspathic porcelain
- Hard Porcelain
- Alumina Porcelain
- High Alumina Porcelain
Technical Ceramics (1,300 – 1,850 °C)
- Coil carrier
- Spark plugs
- amongst other things
A mold of a simple non-textured piece is able to produce 100 pieces, on average. Obviously, it depends on a lot of factors, such as the quality and hardness of the plaster that was used when making it. These mother molds are made in the same way as the first mold, but they are its negative part. For each individual part of the first mold, a mother mold needs to be made. These mother molds are made in silicone and very textured. Ceramic glazing is nothing more than the act of fusing glazes with a ceramic body through fire to achieve certain decorative purposes. Now what exactly is a glaze? A glaze is like a glass coating and it can be glossy, matte, translucent, opaque, smooth and textured. The combinations are endless, all you have to do is test different compositions.
A good ceramic glazing begins with a proper biscuit, well fired and clean, which is basically the state of ceramics after the first firing, required to harden the clay and consolidate its shape.
Before the ceramic glazing, during the first firing, be aware that porcelain and stoneware can’t be fired at a too high temperature in order to maintain some porosity (since they are inherently watertight), allowing the glaze to penetrate the porous properly.
As you can see, producing ceramics is not as easy as it seems. So far, we haven’t even started making ceramic pieces and a lot has been done already.
We have to come up with the design of the pieces, make the model, build strategic molds that may require lots of parts and build a mother mold that will provide us with lots of molds for our production.