16 June 2015


Marshall Colman ceramics 2015

Here straight from the kiln are three vases that I'll be exhibiting at Art in Clay, Hatfield, from 3-5 July. Full details here. They are a selection of three of my current patterns: Parrot, Blue Arabesque, and Harlequin.  I'll be showing vases, jugs, mugs and covered jars in these patterns.  More pictures soon - I have more glazing and decorating to do and two kilns to fire before Hatfield.

For pottery geeks, my pottery is tin-glazed earthenware. The clay is one part red terracotta to three parts white earthenware, which fires to a warm pink. Bisque firing is to 1085 deg.C and glaze firing to 1060 deg.C.  This reverses the usual method in studio pottery, which is to fire bisque at a lower temperature than glaze, and is like the method used in industry. It suits me for two reasons: I glaze with tongs and they mark soft bisque; and it ensures a good glaze fit without crazing. My glaze is a lead borosilicate tin glaze, based on a recipe from my teacher Daphne Carnegy. After many years of experimentation, my firing cycle is fast to 700 deg. then 50 deg. an hour to maturity. I fire in an electric kiln with a computerized controller, but I check with cones (above left) because a pyrometer gives only a rough approximation of what's happening and there can be a significant difference in heat between the top and bottom of my large kiln. There's always a lot of fiddling with controls and vents at the end of the firing to make sure everything is perfect. (Of course, it never is, but that's what you have to aim for.) The colours are a mix of metal oxides and prepared ceramic stains. These are the colours I've used on these three vases:

  • red - high temperature red
  • yellow - Naples yellow + lemon yellow
  • blue - cobalt + copper oxides
  • turquoise - copper oxide + turquoise
  • black - cobalt + manganese oxides.