Ceramic glazing is a coating or layers applied to clay creations and fired in a kiln to make them durable and usable. Glaze makes ceramics strong and waterproof. Without glazing, ceramics would remain porous and would remain unsuitable for holding liquids. Special glazing processes are used to make dinnerware, porcelain and stoneware beautiful.
The glazing process is also used on building materials so they can withstand the elements. An ancient example of glazed building materials is found in China. Glazed bricks were used to create the Iron Pagoda in 1049 CE.
A concern when choosing ceramic glazes is the toxicity, especially when working with children. Most schools schools non-toxic brands such as Amaco glazes to ensure children are safe when they work with clay. Glazes should be lead-free and comply with all FDA guidelines. Usually glazing techniques are taught to older children in grades 7 to 12 with the strict supervision of an experienced adult. Younger children can be easily harmed when they work with glazes and firing so these techniques are typically reserved for children over 11 years old.
Another worry for educators and parents is the type of clay used in a school setting. Children of all ages can learn about pottery by working with clay in their hands but even clay can contain certain toxic elements. Schools prefer to use American art clay because it does not contain New York State talc for maximum safety in classrooms and studios. Children should use talc-free clay or clay make with Texas talc approved by the Art & Craft Materials Institute (ACMI).
ACMI sets industry standards for the safe manufacturing and labeling of lead-free glazes for ceramics. Often you will find Amaco glaze used in a classroom setting because they currently make more than 600 lead-free glazes, giving educators more creative teaching options. Using a combination of toxic-free clay and glaze ensures the safest possible experience for children learning about pottery.
Ceramic glazes may be in a dry or liquid form. Dry glaze is applied over the entire surface of the clay body by dry dusting. When using liquid glaze, the pieces can be dipped right into the glaze. Other options with liquid glaze include pouring the glaze over the creation, brushing it onto the piece or spraying it on with an airbrush or other similar tool.
When you decorate the piece under the ceramic glazing, it is referred to as underglaze. The blue and white porcelain made in China, Japan, England and the Netherlands are examples of underglazing. When you decorate a piece on top of a layer of glazing, it is called overglaze. Artists use overglazing to create glassy, decorative pieces.
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