This is the L3954B engobe recipe but it has 15% Mason 6600 black body stain (instead of the normal 10% Zircopax for white). There is no cover glaze, yet it is durable and absolutely coal black (so a lesser stain % is possible). We have updated the mixing instructions at PlainsmanClays.com and Digitalfire.com pages (showing exact amounts for water, powder, Darvan) and the text on the glossary pages about thixotropy and engobes (read these again and learn to use the engobe process even better). This engobe base is designed to work on regular M340/M390 stonewares (not porcelains). This is exciting because these bodies are so much more robust in drying and much less expensive than porcelains.
Robert has done really valuable work in this research, what an amazing range of color! I am so grateful he shared this with the rest of us. Surfaces are unpolished and unglazed. All are fired to cone 6. Browns are missing, they can be made using iron oxide. For blacks, Mason 6600 is also effective. The blues require lower percentages than shown here, as low as 2% can be effective. Likewise with others, there is an optimal amount for each stain, beyond that, with increases in percentage the color intensity increase will drop significantly. There is another reason to keep stain percentages to a minimum: To reduce the impact on body maturity (and firing shrinkage). Blues, for example, can significantly heighten the degree of vitrification, even melting the porcelain. If you plan to marble different colors, keeping stain percentage as low as possible is even more important, unless you can do fired shrinkage compatibility testing, for example, the EBCT test. Need to develop your own white porcelain? See the link below.
Engobes are high-clay slurries that are applied to leather hard or dry ceramics and fire opaque. They are used for functional or decorative purposes.
Thixotropy is a property of ceramic slurries. Thixotropic suspensions flow when you want them to and then gel after sitting for a few moments. This phenomenon is helpful in getting even, drip free coverage.
L3954B - White Cone 6 Engobe Recipe
Dry and firing shrinkage fitted to Plainsman M390, M340
L3954B engobe page at PlainsmanClays.com
|Materials||Mason 6600 Black Stain|
Sign up at the home page.