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Aventurin glazes Ga-Series are leadless glazes based on frits with a high content of alkaline oxides. Firing temperatures are between 960-1080 °C, but when fired hotter than 1000 °C they run down. The glazes are oversaturated by the iron oxide which crystallize during the cooling and create a little impressive shiny crystals. Glazes are suitable for the dinnerware because they content no lead. However as a rule they are used for decorative ceramics regarding to their higher CTE alfa > 90-120 x 10-7 (K-1), they craze much and after a longer exposition in the water a salt blooming rises. These glazes are very unreliable regarding to reproducibility. It is important to hold firing conditions, thicker glaze layer, firing horizontally and enough long time for the cooling and the proper crystallisation. On the vertical surfaces they run down and in the lower thick layer crystals created. Good results can be obtained by overglazing of the white glaze, for example Dw 153 91.
Glazes of R and Rm series are raw or semiraw (Frit content 10 – 30%) Hi Fire Glazes, leadless, colourless or coloured with ceramic stains or metal oxides, transparent or opaque, mat tor glossy. Their firing limits are 1100 – 1200 °C (semiraw) and 1240 – 1300 °C (raw).
These glazes show very good chemical and mechanical resistence and they are suitable for dinnerware, pottery or stoneware floor tiles. Transparent glazes are suitable for the overglazing of underglaze colours. The glazes are not suitable for very fast firing. They can be used for porcelain stoneware, cordieritte and chamotte bodies too. They can be fired single or double. In spite of their high CTE they do not craze if you fire the right temperature. Glazes P 001 91 or P 016 91 (10-30%) can be used for reduction or increasing of CTE.
Recommended glazing techniques: dipping, spraying.
Glazes of Pw – series are white leadless glossy glazes based on frits. The zirconium silicate as an opacifier is molten in the frit, the glazes show high covering properties and chemical resistance. They are used for the production of dinnerware, tiles or as an additional flux in the semi-raw stoneware glazes for the temperatures 1150 – 1250°C, for example for the sanitary ceramics. They are suitable as majolica glazes and for the further decoration with onglaze colours, decals, gold and platinum preparations and lustres.
They have a low thermal expansion, and therefore a low tendency to craze. They are suitable for white as well as coloured bodies CTE alfa (20-500°C) = 55-75 x 10-7 (K-1). Using the body with higher or lower CTE they can craze (crackle) or shiver (flake off).
The glazes can be coloured to pastel shades with ceramic stains by addition of 0,5 – 8% of stain, they can be mixed with leadless coloured glazes of Pd series. The glazes of G series and Gmu series can be applied upon them in order to create a run-down effect.
Glazes Pm – series are matt coloured opaque glazes, based on frits. Within recommended firing limits 960 – 1020 °C they create a noble satin finish because of wollastonite crystallisation from glass saturated by the calcium oxide. The matt effect is not so stable as in case of zinc oxide based glazes and the glazes fired between 1020 and 1100 °C have semi-matt or glossy surface.
The glazes contain no lead, antimony, arsenic, cadmium oxides or any other toxic substances (except Pm 965 91 – Sb, Pb and exceptions marked in % in the chart) and they are suitable for the production of dinnerware and tiles. They are coloured by ceramic pigments where the contained metals are fixed and there is no danger or their getting loose.
The glazes are suitable to be used on white as well as coloured body with the CTE alfa > 65 x 10-7 (K-1), otherwise they craze. All techniques of glazing are to be recommended.