How does glaze work ceramics

Silica can be obtained naturally from quartz, sandstone, sand, or flint, or it can be manufactured as silica oxide. When making your own glazes, products like quartz, flint, and pure silica can be added as the glass-former. In fact, if you get it hot enough, silica forms glass all by itself. However, silica's melting point approximately F or C is hotter than can be obtained by any ceramic kiln.

Therefore, silica cannot be used on its own as a pottery sealer. Nearly all glazes contain alumina, or aluminum oxide, which acts as a stiffening agent. Without alumina, the glaze would simply slide off the surface of any vertical piece as it's applied, which is not an ideal scenario.

By adding alumina as a clay kaolin, ball clay, or fireclay or as alumina hydrate a white manufactured powder , the glaze can stick to the pottery's surface without coming off.

Not only does alumina stiffen a glaze, but it also helps to disperse fine gas bubbles that can form in the firing process. Additionally, alumina enhances pink hues used in coloring the final piece. Fluxes play the key role in lowering the melting point of silica, making it usable in ceramic glazes. And, like silica, fluxes also promote vitrification the transformation into glass. The most commonly used fluxes in ceramic glazes are obtained from limestone as calcium oxides.

Potash feldspar and soda feldspar are good examples. Glazes get their colors from a wide variety of mineral oxides. Using glazes requires a lot of experimentation and practice. Many factors, like the kind of kiln or the kind of clay you use, impact the final result. Glazes can be applied with a brush or the entire piece can be carefully dipped into a glaze bath. Glazes often require multiple coats and a lot of patience to get them just right.

When that time comes and the piece is dry, you're ready for the glaze firing, where the pottery is heated to maturity. Next, we'll talk about different types of kilns.

Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. It is especially important to use the same clay and firing as you normally use in your work.

Both of these strongly influence the character of the glaze. Ceramic Glazes and Underglazes. Salt Firing and Soda Firing. Ceramic Decorating Techniques. Ceramic Glazing Techniques. Wheel Throwing Techniques. Search the Daily. In This Section. Ceramic Glaze Making For most ceramists the first experience of the technical side of ceramics takes place during glaze making. You Will Need: An accurate scale calibrated in grams. A clean pan or bucket in which to weigh the glaze materials your scale may come with such a pan.

This is called the measuring container. Stainless steel salad bowls come in various sizes and make excellent measuring containers.

A clean bucket in which to mix the weighed glaze materials. This mixing container must be large enough to hold the entire recipe. Transparent is a description of whether you can see trough the glaze to the clay body underneath.

All clear transparent glazes darken the color or the clay or underglaze they are placed upon. Colored transparent glazes will darken the clay body and will often darken and muddy the color of an underglaze that is placed underneath them.

Opaque describes a glaze that cannot be seen through, thus covering the surface and color of the clay. Glossy refers to a glaze surface that is shiny and reflects light.

Matte describes a surface that has no shine and absorbs light with no reflection. So now we come to all the variables and combination names. Semi Transparent is a glaze that has partial transparency just as Semi opaque means it will not completely block out what is beneath it.

Semi- Gloss means the glaze is somewhat shiny but not total reflective just as semi matte refers to the surface being somewhat dull but has a bit of shine. Then there are similar names such as Satin Matte.