![]() Stains are made by fritting coloring oxides together with silica, alumina, and opacifiers in a kiln. In glazes containing zinc, chromium forms brown zinc chromate. Only a very small amount of chromium is needed for this (0.1–0.5% with 5% tin). In the presence of tin oxide in calcium glazes, chromium turns pink. Chromium oxide is not very soluble in glazes, except in high alkaline glazes, where it turns bright yellow-green. If a glaze becomes oversaturated with copper oxide (more than 5%), it turns a matte, metallic black.Ĭhromium oxide (Cr2O3) also known as chrome oxide, gives a reliable green and is used, together with varying amounts of cobalt, in commercial green stains. ![]() In alkaline pottery glazes with low alumina, a bright turquoise may be obtained in oxidation from 1–2% copper oxide. Copper oxide is volatile, and will cause a pink blush on surrounding pots in reduction. Using Oxides to Obtain Great Ceramic Glaze ColorsĬopper oxide (CuO) and carbonate (CuCO3) are used to give green in oxidation and oxblood red in reduction. Low alumina and the addition of boron or barium carbonate also promote blue celadon colors. Iron oxide is also used in celadon glazes, which are gray-green, or blue if there is no titanium present in the glaze or clay body. Ash from different trees contains varying proportions of minerals, which result in a range of colors in the glaze, from olive to apple green. Nickel and titanium will give green in magnesium matte and zinc crystalline glazes.Īsh glazes are often green, when fired in reducing conditions, the color coming from iron oxide present in the ash. Cobalt and titanium or rutile can produce a pale green in high-alumina glazes and slips. Zinc should be avoided in chrome glazes, as it turns the chromium brown. In alkaline glazes, a bright chartreuse green may be obtained using a small amount (0.2%) of chromium oxide. Cobalt and chrome combine to make teal blue-greens. Turquoise can also be obtained using vanadium zircon stains, which are opaque.Ĭhromium oxide gives a reliable green, unaffected by kiln atmosphere, although it is volatile at high temperatures. Other oxides can be added to change the color: iron for yellow-green, nickel for olive green, or ilmenite for blue-green. In oxidation, alkaline glazes with low alumina will give bright turquoise glazes with copper. Copper is volatile, occasionally causing pink flashing on surrounding pots. In reduction, copper reds can be achieved in alkaline glazes containing tin oxide. We now are more acutely aware that the color is affected by the kiln atmosphere and the flux used in the glaze. Today we still use copper oxide to make green pottery glazes. ![]() There are many ways to obtain greens and blues in ceramics, but if you’re looking for a specific hue, this will help you find the right combination. Plus she shares loads of pottery glaze recipes (for all firing ranges). Linda Bloomfield explains the chemistry behind cool ceramic glaze colors ranging from the palest yellow-greens to some terrific teals in this excerpt from her book Colour in Glazes. ![]() So today, I thought I would share some samples of the ceramic glaze colors I obsess over. And by "cool" I mean blues, greens, and turquoises, like these bottles by Lucy Burley. If you've seen anything I have made in the last several years, you know that I'm a little bit obsessed with cool ceramic glaze colors. Pottery Making Illustrated Submission Guidelines.Pottery Making Illustrated's Print Mailing Schedule.Ceramics Monthly's Print Mailing Schedule.Workhouse Clay International ICAN Merit Award.ICAN Making a Difference in Ceramics Award.Annual National K-12 Ceramic Exhibition Award. ![]()
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