Tips and Techniques
General Tips
- The best way to make a hole in greenware is to use a standard drill bit. Just about any size drill bit can be obtained from the local hardware store.
- For large holes create a hole with a drill bit and then enlarge with a sharp clean up tool.
- When making or drilling holes in greenware start from the front as chipping is likely to occur when you break through the back.
- If sanding your greenware is taking longer than you remembered, check your sander, they wear out fast on greenware.
- To get a flat bottom on your greenware by a sheet of sandpaper at the local hardware store. Place the sheet on a flat surface and sand the greenware by rubbing it on the sheet of sandpaper. If you need to do this for a large amount of greenware you can glue the sandpaper to a piece of wood, or any flat surface.
- When working with greenware be sure you clean the sharp edges off, sand to a smooth finish and wipe over with a damp sponge before decorating.
- You should wash your hands before working with greenware as you need to avoid oils and moisturisers contaminating your greenware. This type of contamination can cause the paints to flake off during firing.
- Don't let your underglaze dry out too much before you sgraffito; just let it dry till the shine goes.
- Always wait for the glaze to dry fully after application, before placing in a kiln. As wet glaze increases the chance of popping off, crazing and pinhole marks. It is best to wait several hours or preferably overnight.
- When fixing up drawings use a small fingernail paddle-pop sander to fix up any drawing you do on your piece. Taking pencil marks off with a sponge leads to shiny spots that will not take paints or glazes correctly.
- Use a long liner when outlining your work. It holds more paint and saves you having to reload all the time, minimising the stop and start marks on your outline work.
Glossary of Ceramic Terms.
For a glossary of ceramic terms go to: http://www.ruffordceramiccentre.org.uk/glossary/glossary.htm
Recommended Underglaze Paints
The E-Z Stroke® Translucent Underglazes Colour Chart
The Duncan Ceramics site provides a colour chart for all their ranges,
we use the E-Z Stroke range.
EZ Stroke Range Colour Chart
Kiln temperatures and pyrometric cones.
To find out more about the kiln temperatures we use and the pyrometric cones used to check temperatures in a kiln click here.
Safety
The glazes and underglazes used in ceramics often contain metals and compounds that are toxic or poisonous. Care should be taken including the use of PPE (Personal Protection Equipment) gloves and masks and glasses when considered necessary.
Different products have different risks. You should read the Material Safety Data sheet. For example Duncan E-Z Stroke™ Translucent Underglaze MSDS (PDF)
Humming Kilns?
If you ever thought you heard the kiln's heating elements humming, it wasn't your imagination.
"Some heating elements hum during firing. This the sound of the element coils vibrating in their brick grooves," explains Bob Gieselman, Paragon's directory of operations.
A heating element is formed by winding the element wire around a mandrel, then stretching the element. This produces a coiled wire. When electricity passes through it, each coil generates a small magnetic force. This magnetism attracts the coil to each other.
The electricity that powers a kiln alternates directions. The electricity changes direction 50 times a second (50Hertz). With each change of direction, the magnetism in the coils reverses.
Coils that were attracted when the current went one direction repel each other when the current switches directions.
This constant attraction and repulsion between the coils causes them to vibrate, making the humming.