#MAKE COBALT BLUE PAINT HOW TO#

(I was asked what made the cobalt go fuzzy.) “If you are applying it as an underglaze stain direct on the bisque ware, and then glazing over with a clear glaze, the glaze may be disturbing your decoration, giving you a fuzzy effect. C (cone 10), so you should have no problem at cone 5. “Cobalt is perfect on porcelain, and it doesn’t matter much whether you fire in an oxidising (clean) or reducing (smoky) atmosphere. (My piece at the head of this post uses a cobalt/copper blue and a manganese/cobalt black.) You can experiment with line blends of cobalt and another stain – say stain to cobalt in the ratios 1:9, 2:8, 3:7, 5:5, and see what is best for you. Manganese produces purplish brown, but mixed 50:50 with cobalt produces a warm black.

There are several ways of doing that: you can add red clay, or iron oxide, or copper oxide (which I do) or manganese dioxide. That’s fine if you want a bright blue, but I don’t, so I tone it down. “The cobalt oxide we get today is very pure and very bright. Chinese brush decoration on ceramics (for example, the Qing Dynasty porcelain dish from the V&A illustrated below left) exploits this quality of cobalt oxide to great effect. You can apply the colour as a watery wash, which gives just a hint of blue, to an intense line, which is almost black, and everything in between. Those stains have their uses, but I avoid them because I want to use washes of varying intensity, and for that the simple oxide is best. Ceramic suppliers also sell blue stains, comprising cobalt oxide and other things, sometimes calcined for greater stability.

I don’t know what it is that your potter friend has given you, but the best thing to start with is cobalt oxide, which is readily available although not cheap. “Cobalt blue is the most reliable and stable colouring oxide used by potters. As the question came from someone who declared me “the best ceramist in the world”, I took some trouble over the reply.

#MAKE COBALT BLUE PAINT HOW TO#

I got an e-mail in response to my post Not Quite Monochrome, asking me how to use cobalt oxide in the decoration of porcelain.

Make cobalt blue paint