|Monthly Tech-Tip |
Alternate Names: Copper(II) sulfate pentahydrate, blue stone, cupric sulfate, copper sulphate
Copper sulfate is a blue crystalline powder or granulate. It slowly effluoresces in air. It can be easily dehydrated to its gray anhydrous form by heating, then changed back to crystals by adding water. It is soluble in water, methanol, slightly soluble in alcohol and glycerol.
It is made by exposing copper or copper oxide to a dilute sulfuric acid and then evaporating and the crude sulfate to purify by recystallization. Many grades are available and huge amounts are manufactured so that less pure grades and inexpensive.
Copper sulfate is used in agricultural chemicals, feeds, germicides; in the textile and leather industries, in pigments, electric batteries, as a reagent in analytical chemistry, in medicine, as a wood preservative, for engraving and lithography; in the mining and petroleum industries; for use in synthetic rubber; steel manufacture; and in asphalts. The anhydrous salt is used as a dehydrating agent.
Copper sulfate is employed in ceramics for metallic coloration and is sometimes sprayed as a solution or used as a creamy paste on biscuit for pit firing.
Sulfur Dioxide Toxicity
This gas can be produced when clays are fired in a kiln. What can you do?
Materials that source Na2O, K2O, Li2O, CaO, MgO and other fluxes but are not feldspars or frits. Remember that materials can be flux sources but also perform many other roles. For example, talc is a flux in high temperature glazes, but a matting agent in low temperatures ones. It can also be a flux, a filler and an expansion increaser in bodies.
Additives for Ceramic Glazes
Materials that are added to glazes to impart physical working properties and usually burn away during firing. In industry all glazes, inks and engobes have additives, they are considered essential to control of cohesion, adhesion, suspension, dry hardness, surface leveling, rheology, speed-of-drying, etc. Among potters, it is common for glazes to have zero additives.
Copper (II) Sulfate at Wikipedia
|Density (Specific Gravity)||2.28|
|By Tony Hansen|
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