Old Number: 7
Mason stains in the G2926B base glaze at cone 6
Stains are a much better choice for coloring glazes than raw metal oxides. Other than the great colors they produce here, there are a number of things worth noticing. The percentages may be lower than what you think would be needed, stains are potent colorants. Staining a transparent glaze produces a transparent color, that means it is more intense where the glaze layer is thicker. This is often desirable in highlighting contours and designs. If you add an opacifier, like zircopax, the color will be less intense, producing a pastel shade the more you add. The chrome-tin maroon 6006 does not develop well in this base (alternatives are G2916F or G1214M ). The 6020 manganese alumina pink is also not developing here (it is a body stain). Caution is required with inclusion stains (like #6021), the bubbling here is not likely because it is over fired (it is rated to cone 8), adding 1-2% zircopax normally fixes this issue.
Mason stains in the G2934 matte base glaze at cone 6
Stains can work surprisingly well in matte base glazes (provided they are not too matte). Stains perform differently in a matte host glaze. The glass is less transparent and so varying thickness do not produce as much variation is tint. Notice how low many of the stain percentages are: yet most of the colors are still bright. A good reason to minimize stain concentration is to avoid leaching. We tested 6600, 6350, 6300, 6021 and 6404 overnight in lemon juice, they passed without any visible changes. It is known that MgO mattes, like this one, are less prone to acid attack that CaO mattes. A down-side to this matte mechanism is that chrome-tin stains do not work (e.g. 6006), this is because this does not have the high CaO content needed in the host glaze to develop the color. The inclusion stains 6021 and 6027 work very well in this base. As do the 6450 yellow and 6364 blue. And the 6600 produces an incredible gunmetal black. The 6385 is an error, it should be purple (that being said, do not use it, it is ugly in this base).