Alumina hydrate (Al(OH)₃)
Alumina hydrate is a hydrated form of aluminum oxide used in ceramics to improve the properties of glazes and clays. Its chemical formula makes it a source of alumina with water molecules in its structure, which influences the texture, opacity and drying time of ceramic compositions.
In the firing process, the alumina hydrate loses its water molecules and can be transformed into alumina or even other forms of aluminum oxide, such as calcined alumina. This means that, in certain techniques, it can be used to vary opacity and texture in a single firing, allowing different visual and textural effects to be obtained with a single compound.
When added to glazes, it acts as an opacifier, providing a white, opaque finish that allows a smooth, dull surface, ideal for matte or satin effects. In clay bodys, alumina hydrate provides plasticity, helping to control the drying process and facilitating modeling.Interesting Fact
Alumina hydrate is also used in the manufacture of ceramic fiber, a lightweight, heat-resistant material used as insulation in high-temperature kilns. This fiber provides excellent thermal insulation, allowing high temperatures to be reached and maintained more efficiently.Helpful Tip
To prevent the glaze from becoming too thick or losing transparency, use the alumina hydrate in small quantities and test samples before applying it to large parts. Excessive use can affect the flow and behavior of the glaze, so it is advisable to experiment to find the optimum amount for the type of part and the desired effect.
