Self-Supporting Cones are the most accurate and and , of course, are the easiest to use witness cones available. They provide the same information as Orton Large Cones. The advantage of Self-Supporting cones is that they are the correct height (1 3/4" exposed above the base) and have the 8 degree bending angle built in. They do not require plaques. Self-Supporting cones can be set on any flat surface.
Self-Supporting Cones are available for use between 1087F and 3106F (586C and 1708)C. Cones are numbered from 022 to 32*. Cone 022 is the cone that will deform at the lowest temperature (1087F) and cone 32* is the cone that deforms at the highest temperature 3106F (1708C).
Self Supporting Cones are recommended by glaze and kiln manufacturers to achieve the best results.
Large Pyrometric Cones allow users a practical method to monitor the heatwork (the effect of temperature and time at temperature) inside their kiln. Today they are used by quality conscious manufacturers who want a visual indication of the heatwork in locations throughout their kiln.
Large cones must be mounted in a plaque with the cones mounted at 8 angular degrees. Plaques can be made by hand or purchased through Orton. Orton stocks both 3 hole and 4 hole plaques.
In low fire we like to glaze the bottom of our functional pottery. Because the clays are porous and absorb water we seal the entire piece with glaze. And so that it will not stick to the shelf we use a stilt.