iandol on tue 10 sep 02
To add to the confusion of replacing cobalt as an underglaze colorant in =
a white slip with a glaze tinted with one of the cobalt chemicals, I =
would suggest using both, but keeping the volume of cobalt colour in =
both to a minimum, be it oxide and carbonate. Variations of thickness of =
a transparent blue glaze will change the intensity of the pale blue hue =
transmitted from the slip, as will the angle at which light falls onto =
the surface and the angle from which the surface is viewed.
Nor should we forget that it is possible to use a wash, a suspension of =
Cob Carb of Ox in a solution of CMC or Gum Trag directly onto the clay =
object at leather hard, dry or bisque stages of manufacture.