CALCINATES

Miscellaneous

Family: Raw Mineral
Region: None
Mined At: Unspecified
Raw Mineral: Yes
Generic: No

Notes

(Richard Willis)

In one sense, within the context of “studio ceramics”, clay and glaze ingredients which have had their physical water (H₂O) reduced or removed thermally, in contrast to “anhydrates” which, usually, have had their H₂O reduced or removed chemically; and ingredients, particularly the carbonates, that have had their built-in gases released, especially the CO₂. Minimally, then, calcinates are the deco mposed (oxidized) forms of what were once hydrates or carbonates. Beyond this, calcinates can also be the decomposed forms of what were once “—ides” (sulfides, chlorides, etc.) as well as the “—ates”, “etc.” — which is to say of any molecular form which can be oxidixed by heating. Even the rust of iron (encouraged by heating to room temperature), for example, is in this sense a calcinate.
In the etymological sense, the term signifies raw materials of high calcium content that have had their calcium burned to a purer state. Traditionally, raw materials are calcinated in order to burn off impurities and undesirables such as gas producers (e.g., CO₂ from carbonates) and corrupters (e.g., sulfurs, chlorines, etc.), and to break up solids to (at least) more manageable granules. Occasionally, materials are pre-fired, i.e., “calcined” or “calcinated 8;, at sufficiently high temperatures to burn off chemical as well as physical properties. In the most general sense, almost any “burning” of raw materials that remains below fusion (i.e., melt) conditions and affords an oxidized decomposition is referred to as a “calcination”. Alkalis, as “ashes”, are natural calcinates; nevertheless, when in their carbonate form, though an ash form (re- “soda-ash”, “pot-ash”, etc.), they are not properly calcinates: a fact which stresses that calcination oxidizes a material. Though there are many similarites in behavioral benefits, “calcinates” are not equatable, for important differences, to “ashes” or “frits”.
Though seemingly redundant, oxides can be further oxidized by calcination and made thereby into much more blendable and stronger colorants than uncalcinated ones; and, for this, pigments, whether as single oxides or molecular compounds, are almost always better when calcinated prior to use. see calcination in Appendix II

Authors

Richard Willis (Owner)

XML

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<note>In one sense, within the context of &#147;studio ceramics&#148;, clay and glaze ingredients which have had their physical water (H2O) reduced or removed thermally, in contrast to &#147;anhydrates&#148; which, usually, have had their H2O reduced or removed chemically; and ingredients, particularly the carbonates, that have had their built-in gases released, especially the CO2. Minimally, then, calcinates are the deco
mposed (oxidized) forms of what were once hydrates or carbonates. Beyond this, calcinates can also be the decomposed forms of what were once &#147;&#151;ides&#148; (sulfides, chlorides, etc.) as well as the &#147;&#151;ates&#148;, &#147;etc.&#148; &#151; which is to say of any molecular form which can be oxidixed by heating. Even the rust of iron (encouraged by heating to room temperature), for example, is in this sense a calcinate. 
In the etymological sense, the term signifies raw materials of high calcium content that have had their calcium burned to a purer state. Traditionally, raw materials are calcinated in order to burn off impurities and undesirables such as gas producers (e.g., CO2 from carbonates) and corrupters (e.g., sulfurs, chlorines, etc.), and to break up solids to (at least) more manageable granules. Occasionally, materials are pre-fired, i.e., &#147;calcined&#148; or &#147;calcinated&#14
8;, at sufficiently high temperatures to burn off chemical as well as physical properties. In the most general sense, almost any &#147;burning&#148; of raw materials that remains below fusion (i.e., melt) conditions and affords an oxidized decomposition is referred to as a &#147;calcination&#148;. Alkalis, as &#147;ashes&#148;, are natural calcinates; nevertheless, when in their carbonate form, though an ash form (re- &#147;soda-ash&#148;, &#147;pot-ash&#148;, etc.), they are not properly calcinates: a fact
which stresses that calcination oxidizes a material. Though there are many similarites in behavioral benefits, &#147;calcinates&#148; are not equatable, for important differences, to &#147;ashes&#148; or &#147;frits&#148;. 
Though seemingly redundant, oxides can be further oxidized by calcination and made thereby into much more blendable and stronger colorants than uncalcinated ones; and, for this, pigments, whether as single oxides or molecular compounds, are almost always better when calcinated prior to use. see calcination in Appendix II 

</note>
</notes>
</material>

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CALCINATES

Miscellaneous

Notes

(Richard Willis)

Authors

XML