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From: Mike Smith
Date: 22 Feb 2004
Time: 22:53:37
Remote Name: 68.48.89.106
Any underglaze specifically formulated for greenware application will work. It sounds like you're using Duncan products, so that would be the Cover Coat line.
Many people are afraid to work with underglazes on greenware because it is much more fragile than bisque (personally I prefer it- better control and variety of color), so that's why you are probably being told that.
You apply the underglaze, fire to 04, glaze the piece and fire to 06.
If you are using Bisque underglazes like Duncan's Concepts (which are essentially formulated glazes that are more concentrated), you are applying the underglaze to bisque (the piece has already been fires to 04). You apply the underglaze, glaze (if necessary depending upon the technique you are using), and fire to 06.
Note: if the piece you are doing is to be used for dinnerware, make sure all of the products you are using are safe for dinnerware. Also, there are many in the industry who prefer to fire dinnerware to a higher cone (03 or 02) in the greenware stage- this is an argument that's been going on for (oh say) 50 years or so. It produces a harder ware that is more resistant to chipping and yadda yadda yadda, but it is personal preference. If you decide to do that, make sure that your glaze product is still fired two cones COOLER than the clay body and make sure that the glze/ underglaze has been tested for the higher temperature range.
This is probably WAY more information than you had hoped for, but it's stuff that's been forgotten along the wayside in the past ten years of ceramics and some of it really should be resurrected if not just for the sake of education.
Mike