I recently took Kathy Wilcox's Quill & Pen class. She explained the use of underglazes/overglazes, pigments, firing temperatures, and so much more. She is an amazing teacher and very talented artist. Here are some photos of the from her class.

She makes hundreds of test tiles that show different techniques. On the back of each one are her personal notes of how she acheived each tile.

She uses a variety of stencils/materials in her designs...

Her demonstrations/instructions were wonderful...