Ceramicware Defects Handbook/Colour flow

Defects description
Some colour pigments especially cobalt blue and nickel can be affected by covering glazes during firing which will produce blurred outline The problems are more noticeable if the decorations are at slanted and not flat-down surfaces

Causes & solutions

 * Glaze is too thick. Thicker glaze may "flow" down and drag colour pigment with it. Thinning the glaze as realistically possible by applying lesser glaze.
 * Lower the glaze firing temperature for the glaze to melt lesser molten glaze (To minimiises potential of molten glazes "dragging" colour pignments)
 * Adding 5%-10% alumina in the glaze to increase molten glaze viscocity
 * Shorten the soaking period as realsitically as possible (Also not too short until the glaze layer is not properly melted)