PSH 540i Black Clay 540i is a unique, multi-purpose, brown-black cone 6 clay pigmented with non-toxic iron oxide. While it is one of our best selling stonewares, it is important for new users to be aware that it is more reactive and outgases more than other clays that we produce and, as a result, might cause defects such as orange peel surfaces, fine bubble clouding or cratering in some glazes. To achieve the darkest colour possible, 540i is formulated to be highly vitreous, making it more susceptible to bloating when overfired than other, less glassy stonewares. 540i can be fired lower, to cone 5, and remain a fully functional tableware body but with less depth of colour. 540i is not recommended for microwave ware due to excessive heating.
