Once you have fired the piece for 2-1/2 minutes, let the charm cool to room temperature. Once cooled, there are a few things you can do to test to make sure the piece is fired correctly.
Drop the piece onto a metal surface to see what it sounds like--it should sound metallic and not like a thud or hollow.
Fire a test piece that is the same size as your finished design, following the same instructions, allowing the piece to cool to room temperature. Bend the piece to see if the firing time worked for the thickness you are working in. If the test piece is brittle, refire the test piece and test it again. If it bends rather than breaks, repeat firing the finished design and hold the temperature/orange glow for the longer period of time.
Note: When firing with a torch, it is advisable to wear safety or didymium glasses to help prevent damaging your eyes from staring at the orange glow for extended periods of time.
- Tammy Honaman, Author, Jewelry-Making Expert and Educator