Plainsman Fire-Red reduction fired vase

Fire-Red is a 50:50 mix of St. Rose Red and M2 with 10% A1 bentonitic clay. The St. Rose is a red fireclay, not useful on its own in reduction firing because it is too refractory. The M2 supplies iron staining but also enough natural feldspar to mature the body enough to make it strong. The A1 contributes iron pyrite speckle and plasticity. In heavy reduction, with a little more feldspar added, this body can fire metallic. The glaze G2571A bamboo.

Related Pictures

Iron red reduction clay suitable for functional ware? How?

This picture has its own page with more detail, click here to see it.

This is a high iron two-material stoneware fired in reduction, purely a test body we are working on. Normally such bodies are rendered unsuitable because of black coring associated with FeO. But 10% added Custer Feldspar solves that problem, combining with the iron to vitrify the body to excellent fired strength (it does have 5% porosity but this is mainly due to the cavities formerly occupied by the iron pyrite particles. The color and iron speckle are contributed by both of the raw materials in the body. Saint Rose Red supplies most of the iron to produce the red coloration. A1 bentonitic clay adds plasticity and contributes the pyritic iron particles. The fired bars of this body show it at cone 10 reduction (top) and cone 10 oxidation down to 7 (downward from top). Adding just a little more feldspar produces a metallic firing surface! The glaze is GR10-CW, pure Ravenscrag Slip with 10% talc opacified with a little Zircopax and tin oxide.

Saint Rose Red being delivered. Look what it does at cone 10R!

Dump trucks delivering the bright red lump clay to the Plainsman plant

This picture has its own page with more detail, click here to see it.

We get this clay from St. Rose, Manitoba. Four tandem loads arrived this week. Just seeing the pile inspires me to make more pieces! It is a red fireclay and it is highly unusual. St. Rose Red has issues. They at first seem to be problems, but in combination they give it magic powers! It fires with very heavy iron speckling. The iron pigmentation is so high that it burns almost black at cone 10R. It has low plasticity. It shivers glazes: The vase on this picture lasted an hour after kiln exit, it spontaneously fractured because of the outward pressure from the under-compression glaze on the inside. But, by combining St. Rose Red with our more vitreous clays, which are highly plastic, we can make H440 and H443. A mix of only 45 St. Rose with 40 Ball clay and 15 feldspar produces a rustic metallic surface (like the cup shown). Such a body cannot be made from a low fire red clay (like RedArt), it would just warp and collapse in the kiln. It is the refractory character, heavy pigmentation, iron speckling and low plasticity of St. Rose that make metallic ware possible.

Videos

Links

Glossary

Reduction Firing
A method of firing stoneware where the kiln air intakes and burners are set to restrict or eliminate oxygen in the kiln such that metallic oxides convert to their reduced metallic state.

Got a Question?

Buy me a coffee and we can talk