A secondary flux is a

ceramic flux Fluxes are substances, usually oxides, used in glasses, glazes and ceramic bodies to lower the high melting point of the main glass forming constituents, usually silica and alumina. A ceramic flux functions by promoting partial or complete liqu ...

(such as

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

oxide) which does not act as a good flux (i.e., lower the melting point of the mixture) alone, but is effective when used in combination with other fluxes. They also tend to act as "anti-fluxes" at lower temperatures, and may produce matt or opaque glazes under those conditions. For example,

calcium oxide Calcium oxide (formula: Ca O), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term '' lime'' connotes calcium-containing ...

is generally used with

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

and by itself has little fluxing effect at

pyrometric cone Pyrometric cones are pyrometric devices that are used to gauge heatwork during the firing of ceramic materials in a kiln. The cones, often used in sets of three, are positioned in a kiln with the wares to be fired and, because the individual c ...

6 but does act as a flux at cone 8.. When use calcium with lead it gives low melting temperature to glaz. A primary flux is a

metal A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, electricity and thermal conductivity, heat relatively well. These properties are all associated wit ...

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

such as

which acts as a flux at all temperatures.

References

* David Scott (1998) ''Clays and glazes in studio ceramics'', {{ISBN, 1-86126-138-1 The Crowood Press pp. 65-66. Ceramic materials

See also

References