WATER

Miscellaneous

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

Notes

(Richard Willis)

The liquid state of H₂O, water, is the most used and the most ignored ingredient of clays and glazes. Water is among the principal determinants in whether clay and glaze recipes will yield what they claim from one place to another, and, say, many a good recipe from China has been trashed in California for no other unworkability than the precising waters called for and their extraordinary differences. A common saying among ceramists is that good recipes, like goo d wines, do not travel well. Other factors, such as firing conditions (oxygen-rich sea-level air versus oxygen-lean mountain-level air, wood fuels versus petroleum fuels, varying temperature and draft zones from kiln to kiln, etc., etc.) also determine the travelability of recipes, but it remains that, as though to spite common sense, water is the most ignored.
Precising analyses aside, common sense advises, for example, that underground water near a salt-rich lake, lagoon or sea will likely be rich in sodium; river water will be rich in the minerals composing the earth through which it flows (see soils); and rain water, though essentially a distilled water, will vary from place to place and season to season and from first drops to hourly downpours depending on what it is washing and bringing down out of a city’s chemically-l aden air or a desert’s dust-laden clouds. Often as not, an indiscriminate addition of a bucketful of water to innocently wet a carefully formulated blend of clay or glaze powder can be the equivalent of throwing in a handful of unknown chemicals, and, then, when results are far from what was hoped for, there is a naive scowl for perplexity.
chemical water
Sea, river, rain, etc., waters are referred to as “physical” waters within the contexts of ceramics in the sense that they are materials that ceramists use in predominately one of its three possible physical states, that is as a liquid rather than as a solid (ice) or gas (vapor). However, there is another liquid form of water that is also very important to the ceramist, which is called its “chemical” form, known chemically as H₂O, which, t hough having weight and occupying space, is relatively hidden, tucked away as part and parcel of the crude materials (in the earths of oxides, minerals, rocks, etc.) which will convert to vapor upon heating or to a solid upon cooling. Chemical water is also the residual H₂O which remains imbedded as a liquid even after a material has been heated to boiling (100ºC) and the H₂0 which remains a liquid even after the material has b een cooled to freezing (0ºC). For the ceramist, physical water is dangerous because it can explode pieces while converting to vapor when heated too quickly. Chemical water is a stubborn liquid, often resisting a conversion to vapor (gas) even at calcinating (i.e., oxidizing) temperatures of 650ºC and beyond, but so necessary to fusion and melting of a formula’s “dry” ingredients. Its physical properties (its density, its weight and the space it occupies, etc.) — its “mass& #148; — must be eliminated and compensated for in order that a piece of clay or glaze can mature from crude to ripe, so to speak, in the metamorphosis of conglomerated earths to ceramic pieces. If not, the finished product would be analogous to a piece of glass with visibly trapped bubbles, undesirable aesthetically and structurally.
It is this chemical water that is indicated by molecular formula notations and that must be figured in clay and glaze recipe calculations as part and parcel of a given material.
Physical water, on the other hand, is calculated separately — as an independent ingredient. For example, when one sees “SnCl₂, 2H₂O” he is expected to know that two molecules of chemical water are present and, thereby, that this form of tin is a hydrate; while if one sees only “SnCl₂”then he is expected to know that there is no molecule of water present and that thi s form of tin is an anhydrate. On the other hand, if one sees “SnCl₂+ water” he is expected to know that physical water is to be added for purposes of wetting and thus for ease of handling. Where critical, as in slip slurries, a given recipe will precise the amount of water, but rarely elsewhere, as in glaze recipes. The reason is simple, but important: the quality of the water is what is critical, not so much its quantity; and since the quality varies so greatly from one studio to another the recipe presumes the futility of prescribing an unknown.

Authors

Richard Willis (Owner)

XML

<?xml version="1.0" encoding="UTF-8"?>
<material name="WATER" descrip="" generic="0" rawmineral="1" searchkey="" loi="0.00">
<notes>
<note>The liquid state of H2O, water, is the most used and the most ignored ingredient of clays and glazes. Water is among the principal determinants in whether clay and glaze recipes will yield what they claim from one place to another, and, say, many a good recipe from China has been trashed in California for no other unworkability than the precising waters called for and their extraordinary differences. A common saying among ceramists is that good recipes, like goo
d wines, do not travel well. Other factors, such as firing conditions (oxygen-rich sea-level air versus oxygen-lean mountain-level air, wood fuels versus petroleum fuels, varying temperature and draft zones from kiln to kiln, etc., etc.) also determine the travelability of recipes, but it remains that, as though to spite common sense, water is the most ignored. 
Precising analyses aside, common sense advises, for example, that underground water near a salt-rich lake, lagoon or sea will likely be rich in sodium; river water will be rich in the minerals composing the earth through which it flows (see soils); and rain water, though essentially a distilled water, will vary from place to place and season to season and from first drops to hourly downpours depending on what it is washing and bringing down out of a city&#146;s chemically-l
aden air or a desert&#146;s dust-laden clouds. Often as not, an indiscriminate addition of a bucketful of water to innocently wet a carefully formulated blend of clay or glaze powder can be the equivalent of throwing in a handful of unknown chemicals, and, then, when results are far from what was hoped for, there is a naive scowl for perplexity. 
chemical water 
Sea, river, rain, etc., waters are referred to as &#147;physical&#148; waters within the contexts of ceramics in the sense that they are materials that ceramists use in predominately one of its three possible physical states, that is as a liquid rather than as a solid (ice) or gas (vapor). However, there is another liquid form of water that is also very important to the ceramist, which is called its &#147;chemical&#148; form, known chemically as H2O, which, t
hough having weight and occupying space, is relatively hidden, tucked away as part and parcel of the crude materials (in the earths of oxides, minerals, rocks, etc.) which will convert to vapor upon heating or to a solid upon cooling. Chemical water is also the residual H2O which remains imbedded as a liquid even after a material has been heated to boiling (100&ordm;C) and the H20 which remains a liquid even after the material has b
een cooled to freezing (0&ordm;C). For the ceramist, physical water is dangerous because it can explode pieces while converting to vapor when heated too quickly. Chemical water is a stubborn liquid, often resisting a conversion to vapor (gas) even at calcinating (i.e., oxidizing) temperatures of 650&ordm;C and beyond, but so necessary to fusion and melting of a formula&#146;s &#147;dry&#148; ingredients. Its physical properties (its density, its weight and the space it occupies, etc.) &#151; its &#147;mass&
#148; &#151; must be eliminated and compensated for in order that a piece of clay or glaze can mature from crude to ripe, so to speak, in the metamorphosis of conglomerated earths to ceramic pieces. If not, the finished product would be analogous to a piece of glass with visibly trapped bubbles, undesirable aesthetically and structurally. 
It is this chemical water that is indicated by molecular formula notations and that must be figured in clay and glaze recipe calculations as part and parcel of a given material. 
Physical water, on the other hand, is calculated separately &#151; as an independent ingredient. For example, when one sees &#147;SnCl2, 2H2O&#148; he is expected to know that two molecules of chemical water are present and, thereby, that this form of tin is a hydrate; while if one sees only &#147;SnCl2&#148; then he is expected to know that there is no molecule of water present and that thi
s form of tin is an anhydrate. On the other hand, if one sees &#147;SnCl2 + water&#148; he is expected to know that physical water is to be added for purposes of wetting and thus for ease of handling. Where critical, as in slip slurries, a given recipe will precise the amount of water, but rarely elsewhere, as in glaze recipes. The reason is simple, but important: the quality of the water is what is critical, not so much its quantity; and since the quality varies
so greatly from one studio to another the recipe presumes the futility of prescribing an unknown. 

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

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WATER

Miscellaneous

Notes

(Richard Willis)

Authors

XML