Matte glazes are the opposite of glossy ones. They are more difficult to achieve and the matte mechanism can be fragile (lost by slight changes in firing, for example) and the surface non-functional (cutlery marking and staining are common).- The ratio of silica to alumina is mainly responsible for the degree of matteness in glazes. In the absence of boron, ratios of less than 5:1 are generally quite matte; ratios of greater than 8:1 are usually glossy in the absence of high titania, zinc, magnesia, or calcia (which cause volatile melting or crystallization during freezing). Ratios of 1:18 are possible, but certainly not typical. If a glaze remains matte when fired higher, it is a true alumina matte.
- Titanium can be used in glazes to produce a matte surface with increasing amounts of crystallization in amounts up to 25%. The effect works in most stoneware glazes and is better when the glaze is slow cooled.
Oxides - MgOMagnesia is well known for the pleasant vellum 'fatty matte' and 'hares fur' tactile and visual effects that it produces around 1200C, especially in reduction firing (dolomite matte). The mechanism is phase separation of the suddenly melting MgO, but MgO can also produce matte effects at lower temperatures as a refractory melt-stiffening additive.
Oxides - SiO2Low silica high alumina glazes produce matte effects. The silica:alumina molar ratio is considered a good indicator of this type of matteness. A ratio of 5:1 is matte; 10:1 is glossy. The high alumina stiffens the glaze melt preventing it from solidifying to a flat surface.
- Even in small amounts, rutile tends to matte the surface of leaded glazes.
Oxides - CaOHigh molar amounts of calcia combined with adequate silica and preferably lower alumina will form a calcium silicate crystal matte (lime matte). The presence of zinc will increase the size of crystals.
Oxides - BaOBaria is well known for its tendency to cause the growth of a fine mesh of micro crystals to produce a silky matte texture.Oxides - SrOLike calcia and baria, it will produce a fine crystalline mesh to give attractive satin matte surfaces.
- Dolomite can be used in glazes melting over 1170C to produce a silky matte surface. This occurs because high percentages of dolomite help to form diopside crystals (CaMg(SiO3)2) on cooling, and it is these that produce the popular butter-matte effect. This effect is most pronounced in reduction.
- In low temperature glazes magnesium carbonate in amounts to 15% acts as a refractory, remaining in suspension in the glaze melt to produce a white opaque matte glaze.
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