Expert: Leisha Hiester - 1/11/2009

Question
I've used Pam cooking oil on a glass bowl to use it as a mold for a slab of clay to make a similar size bowl.  Now that there is Pam on the inside of the greenware bowl, can I paint at this stage with underglaze colors or must I first bisque fire?

Answer
Anne,
I would recommend bisque firing first to burn off any residue of the oil. I haven't personally used Pam, but I use WD-40 in a similar fashion in my studio. Oils, even from your fingerprints can leave marks on the clay causing glaze not to stick well.
Leisha