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Play it Safe!
Clay is a great way to add a 3-dimensional project to your art curriculum. (or for use in the general classroom too!) After teaching ceramics I've picked up many tips and recommendations when working with clay to help you along.
Clay generally comes in plastic bags. If you are working with a large class, investing in a garbage can or plastic tote is a great way to store clay. You can open up more than one bag at a time and throw the clay into the can. What students do not use at the end of class, they toss back in to keep it moist. Even over holiday break, just toss a wet towel over the clay and make sure the lid is on tight, and the clay will stay wet. But don't throw away those plastic bags either. They work great for student's in progress work. They can write their names on a piece of masking tape, stick it to the bag, and wrap up their project until the next class.
Working with Clay
Any clay taken out of the clay bucket needs to be wedged (kneaded) in order to expel any air bubbles. In my classroom I had a stack of canvas mats that the students used to work on. Clay will stick to many hard surfaces and when you are cutting and shaping parts of your project or rolling out slabs of clay, this can be frustrating. It is also helpful to lay a damp paper towel over any unused clay to help it retain moisture while working. Continual exposure to air will dry it out. It is important to minimize the amount of dust in the air that clay can generate. Dust is the biggest health hazard when working with clay and is damaging to lungs. For this reason, all clean-up should be wet-based. Tables and other work surfaces wiped with a wet sponge and continually rinsed, floors wet-mopped, and un-used scraps put into buckets before they dry out. Students should never eat or drink while working with clay to avoid ingesting dust.
Suggestions for Projects
Students should take caution in building their clay pieces. Failure to do so can result in damaging their projects and others during firing.
- Clay pieces should be no more than ¼ to ½ an inch thick.
- Clay objects must be hollow, with a hole somewhere for air to escape. Any trapped air will cause ceramic pieces to shatter.
- Clay projects must dry for a minimum of a week and be bone dry before bisque firing.
With so many students working on clay projects, it can be difficult to remember when a student finished their project and how long it's been drying. A five shelf cabinet labeled by day of the week is a great solution to this dilemma. When students finish their clay piece, they place their object on that day of the week's shelf. This makes it easier to figure out if a piece is ready for kiln firing or not.
- Underglaze/matt glazes are NOT shiny.
- Glaze work should be done on a paper towel. This makes for easy clean up.
- Shake glaze jars before use. Make sure lid is on tight!
- Clean up any spills ASAP, especially if you get glaze on your clothes.
- For the best coverage, apply two even coats of glaze to a ceramic piece.
- Do not over-do it or under-do it. Too much glaze will run, too little will result in uneven, un-shiny surface.
- DO NOT GLAZE THE BOTTOM OF A CERAMIC PIECE!
- Light colored glazes do not work well over dark glazes unless you are using underglaze.
- For ceramic pieces that contain a lot of detail in design, you should use underglaze.
- Transparent glaze (pink stuff) is a clear glaze coat, which you put over underglaze to make your ceramic piece shiny.
- Make sure to replace lid tightly and return glaze to proper shelf when you are finished.
- Use a different brush for different colors or wash brushes thoroughly to re-use.
Since students are mainly interested in what glazes look like after they are fired, I've found it helpful to organize them this way by color. Fired tiles with glaze samples can help students choose or you can laminate catalog pages showing fired glaze colors. It is very important that students recognize the difference between dinner ware and non dinner ware safe glazes especially if they are creating something which will hold food or beverages. Many non dinnerware safe glazes contain lead and can be poisonous.
When the kiln is firing, it is hot! Firings should be done while students are not in attendance. If that's not possible, students should be kept away from the kiln area to avoid burns. Ventilation is essential as the kiln will release toxins during firing. Even after the kiln has completed firing, objects will need time to cool down before being handled or removed.
For more information about art safety in your classroom, check out the book: Safety in the Artroom.