This is a problem I have had intermittently since I started making pottery at home in 2010, and lately it seems to be happening to more pieces each firing.
1. Are these pinholes or blisters? Sometimes they are sharp on the edges.
2. How can I correct this?
Helpful (?) details:
I am doing a slow bisque firing to cone 04. I hold for 10-15 minutes at peak depending how tight I've loaded the kiln.
Bisque firing profile: 80/hr to 250F, 200/hr to 1000F, 100/hr to 1100F, 180/hr to 1