Hi Tstst! Regular contributor Glazenerd has posted bisque schedules here, with some details on why the holds ...looking... Overview Some specific defects; see "Cone 6-10 Firing Schedule for dark or red bodied clay bodies."  in last post See also   Perhaps someone familiar with your clay can add more - hope the above links are a good start? There are several others threads on the subject here as well. My kiln is fully manual, so I'm watching for the critical