These paints are suitable for general glass painting but should not be used on surfaces that come into contact with food. Transparent glass colors are not resistant to acid or alkali influences and if so exposed, easily become matt and lose transparency. Do not apply to the tin side of float glass. The colors are generally mixable with each other. However, do not mix the precious metal containing colors (product codes that begin with “P”, “PR” and the Purple C 60/I) with the remaining colors. Also, F7137 Opal orange, F7138 Opal red, and F7140 Opal orange are not suitable for mixing with the other colors. Do not apply these paints to the tin side of float glass without testing first. Transparent colors can be applied by brush, airbrush (spraying) or by screen printing. Applying the paint too thickly may result in the paint cracking. To brighten the colors, mix with Flux 83. By adding 20–30% flux you can decrease the firing temperature by about 20°C (36°F). The kiln exhaust should be very effective up to about 450°C (842°F). A fast temperature increase, short peak time and a slow cooling down is best.