Posted 17 July 2014 - 12:04 PM
Stains usually are blends of materials supplying chemistry that are there to influence and stabilize the colors produced. They are melted and ground... but I'm not sure I would use the term "frit" when looking at them. The colors porduces form a given colorant are GREATLY impacted by the chemistry of the glaze material that they are out into. Stains were developed to help remopve SOME of this variability. They are not "bulletproof" in this regard: see the manufacturer's information about the nature of the bases glazes they work in.
Typically... they are not "oversupplied" with a particular fluxing oxide..... so they do not typically behave like using an "oxide wash" where usually you have a saturation of a particuler oxide on the suirface of the clay. As Neil says... to use them like washes usually needs the additiona of some material supplying some flux and a glass former.
Professor of Ceramics; New Hampshire Insitute of Art
Guest Professor, Wuxi Institute of Arts and Science, Yixing, China
Former President and Past President; Potters Council