The Case of the Disappearing Colors



The colors as seen under normal conditions



Under strong light dark blue appears from below the surface

 I have recently come across something quite extraordinary in my work with soluble salts. This is the absorption of the color into the body which is only revealed when held over a strong light source. The example shown above has a weak solution of Cobalt Chloride painted on then resisted and painted with Potassium Dichromate and has all but disappeared except for a plae green on the surface. When held over a strong light (apologies for the poor image) the piece shows a definate blue trapped beneath the surface, and the resisted area a pale green. What is the cause of this? My theory is that the body was too absorbant after bisque firing. I have found that if the piece is warmed before painting on the salt solutions and fired almost immediately the decorating is completed this problem disappears. Anyone got any other ideas on what could cause this. I would really be interested to hear from you.