Disposing of Glazes

I mix my own glazes from dry ingredients, and therefore often have
small test batches that just don't work out. My question is what is
the proper way to dispose of these glazes? My first instinct is to let
them dry out and just toss them in the garbage, but there has got to be
a better (environmentally friendly) way! What do you folks do with
unwanted glazes?
Any suggestions will be most appreciated!
Anna
www.annaspots.com

"anna" wrote in message
oups.com...
I mix my own glazes from dry ingredients, and therefore often have
small test batches that just don't work out. My question is what is
the proper way to dispose of these glazes? My first instinct is to let
them dry out and just toss them in the garbage, but there has got to be
a better (environmentally friendly) way! What do you folks do with
unwanted glazes?
Any suggestions will be most appreciated!
Anna
www.annaspots.com


First off what do you put in your glazes? For the most part glazes are
pretty benign earth materials unless you are breathing them in or soaking
your skin with them. You don't want to be breathing silica but in itself it
is just sand. It is only if you are adding lead or something of that like
that it is a problem in the environment (well copper will certainly keep
fungus from growing so it isn't benign in that regard...). I don't see why
it can't be incorporated into the garden soil or compost pile (for flower or
shrub area only - not food garden). But! only if you know what the
ingredients are and are sure that they won't be contaminants. This is just
my opinion and not based on data.

www.digitalfire.com has an excellant materials data base and articles on
what materials to be concerned with.

On 15 Nov 2006 09:54:27 -0800, "anna" wrote:

I mix my own glazes from dry ingredients, and therefore often have
small test batches that just don't work out. My question is what is
the proper way to dispose of these glazes? My first instinct is to let
them dry out and just toss them in the garbage, but there has got to be
a better (environmentally friendly) way! What do you folks do with
unwanted glazes?
Any suggestions will be most appreciated!
Anna
www.annaspots.com


I favor the "traditional" approach: Mix them all
together in one huge batch, and then figure out
what the heck you can use it for! grin

Seriously, you may in fact be able to use the
combined batch as a liner glaze for the inside
of bottles or something where the brownish-green
color won't be a problem. You may find that the
properties of all the test batches tend to average
out, so that runny glazes cancel stiff ones, etc.
And if you do have a use for the combo glaze,
but some property is still a bit off, you can probably
adjust it via a simple line blend test.

Just a thought!


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

good comment of a liner glaze....

also, everyone has a junk pot somewhere, so to add the glaze to the
inside of a junk bowl & fire it will put the glaze into an inert
condition. when in doubt, fire it.

but some glaze material IS very good for gardens so do a little
research. i found that dolomite is excelent for gardens. calcium is a
great way to help insure blooms turn to strong fruit.

see ya

steve



On Nov 16, 5:31*am, (Bob Masta) wrote:
On 15 Nov 2006 09:54:27 -0800, "anna" wrote:

I mix my own glazes from dry ingredients, and therefore often have
small test batches that just don't work out. *My question is what is
the proper way to dispose of these glazes? *My first instinct is to let
them dry out and just toss them in the garbage, but there has got to be
a better (environmentally friendly) way! *What do you folks do with
unwanted glazes?
Any suggestions will be most appreciated!
Anna
www.annaspots.comI favor the "traditional" approach: *Mix them all
together in one huge batch, and then figure out
what the heck you can use it for! *grin

Seriously, you may in fact be able to use the
combined batch as a liner glaze for the inside
of bottles or something where the brownish-green
color won't be a problem. *You may find that the
properties of all the test batches tend to average
out, so that runny glazes cancel stiff ones, etc.
And if you do have a use for the combo glaze,
but some property is still a bit off, you can probably
adjust it via a simple line blend test.

Just a thought!

Bob Masta
dqatechATdaqartaDOTcom

* * * * * * D A Q A R T A
Data AcQuisition And Real-Time Analysis
* * * * * *www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

Sorry, I can't find my link to this so I will post it. If you do a 'find'
for 'toxic' you will find those materials this site considers toxic. My
rule has always been, if its a colorant beware. I can't live without cobalt
but generally I try to avoid any material that is not benign simple because
I'm too absent-minded to be trusted to keep track of more than a couple of
items at any given time. KISS (keep it simple stupid) works for me.


GLAZE MATERIALS
Glaze Materials Coding:
Preceding each material are letters representing their primary function in a
glaze, in descending order of their functional impact.
F = Flux
A = Alumina (refractory)
G = Glassformer
C = Colorant
O = Opacifier
= Toxic
A
Alumina Hydrate-Al2O3 3H2O
Occassionally used directly in glazes to increase hardness, viscosity and
stability. Also aids in craze resistance. Used in excess, it will tend to
give a matt surface. Most commonly used as a kiln wash, especially in
salt-glazing due to high refractory quality.
A
Alumina Oxide-Al2O3
(Calcined alumina hydrate) A refractory material contributing to a brilliant
or matte finish in glazes, depending on amount used. As with alumina
hydrate, normally alumina is introduced to glaze as a constitutent in clay
or feldspar.
C/G/O/
Antimony Oxide-Sb2O3
An opacifier for low fire glazes. Also used as a colorant producing yellow
to cream, stronger yellow with iron present. Toxic.
F/
Barium Carbonate-BaCO3
Used in glaze formulas as a flux at high temperatures. Produces frosty,
silky, soft matts. Makes colors more brilliant. Produces turqoise from
copper, yellow from iron, bright blue from cobalt. Also used in red clays
(2-3%) to help prevent soluble salt scum on the surface after firing.
Insoluble in water. Strontium Carbonate is sometimes used as a substitute.
The dust is toxic.
F/
Barium Sulfate-BaSO4
Used in some porcelain enamels to reduce shorelining and dimpling. See
Barium Carbonate for use in glazes. Toxic in raw form.
Clay
Bentonite-Al2O3 4SiO2 9H2O
A fine-grained clay that is quite sticky, very plastic with a very high
shrinkage. It swells considerably when wet and should be mixed with water
before introduced to a clay or glaze. Used in small percentages (1-3%) in
body plasticity and glaze suspension.
F/O
Bone Ash-Ca3(PO4)2
(Calcium Phosphate) Originally made of ground calcined animal bone; used in
bone china (up to 50%) to aid body translucency and strength. A flux and
opacifier in glazes. May render surface texture in some low-fire glazes.
Calcium Phosphate is the version normally used since it contains less
contaminates.
F/G
Borax-Pdr-Na2O 2B2O310H2O
Used in glaze formulas as a low temperature flux in lieu of lead, but is a
strong flux at all temperatures. Usually needs to be used in conjunction
with 2-4 other fluxes. Brightens colors. Often produces milky blue
opalescence, cloudy and spotted coloration. Very soluble in water, most
often used in a stable fritted form.
C/
Cadmium Oxide-CdO
Used to produce yellows, oranges and reds in low fire glazes. Very toxic in
raw form and prone to leaching from fired glaze.
F
Calcium Carbonote-CaCO3
(Whiting) A source of calcia in glazes. Used as a high temperature flux and
as a matting agent at lower temperatures. It produces a hard, durable glass
and renders a glaze less viscous in its molten state which can reduce
pin-holing.
Calcium Chloride-CaCl2
A flocculant used in very small amounts to keep particles in suspension.
Soluable.
F/O
Cerium Oxide-CeO2
An opacifier at low temperatures. Gives yellow when used with titania.
C/
Chromium Oxide, Green-Cr2O
A refractory ceramic color. Used with tin to produce pinks or with zinc for
browns. Extermely potent colorant. Very little is required to produce strong
greens in clays or glazes. Volatile when fired over cone 7. May affect the
color of adjacent ware in the kiln. Toxic.
Clays-Al2O3 2SiO2 2H2O
Used in glazes to help the glaze fuse to the body and help keeep the
ingredients suspended. A common source of alumina and silica in glazes. See
Clays-Raw section for details.
C/F/
Cobalt Carbonate-CoCO3
A very potent pigment, producing blue colors. Color variations: in lead
glazes, pale to dark inky blue; in barium, strontium and alkaline glazes,
brillian ultramarine blues; in magnesium glazes, pink lilac and purple blue;
in zinc glazes, soft grey blue. A very potent pigment, producing blue
colors. Best source of cobalt for glazes due to fine particle size. Toxic.
C/F/
Cobalt Oxide-CoO
A glaze colorant that produces reliable strong blue hues. Used in brushed
oxide decoration. Stronger and grainier than cobalt carbonate. Dark
blue-black in powder form. Toxic.
C/F/
Cobalt Sulfate-CoSO4
A water-soluble cobalt used in lustrous blues in raku firings. Neutralizes
yellow color of white slips. Soluable. Toxic.


C/
Copper Carbonate-CuCo3
A light green/ turquoise color in powder form. Very sensitive to temperature
and atmosphere to produce colors from red (good reduction in a soda base) to
turquoise, blue-green or purple in barium and alkaline glazes, to orange,
pink or grays in magnesium glazes, to metallic copper (raku). All coppers
are strong fluxes. The carbonate decomposes in hot water. Toxic.
C/
Copper Oxide-Black-CuO
(Cupric) Black dry color. Normally used wherever copper oxide is called for
and red or black is not specified. Copper tends to volatize somewhat at high
temperatures affecting adjacent colors. Toxic.
C/
Copper Oxide-Red-Cu20
(Cuprous) A concentrated copper form. Reverts to CuO in oxidation. Toxic.
C/
Copper Sulfate-CuSO4
A blue powder used to obtain greens and reds depending on firing atmosphere
and accompanying chemical in glaze, especially in Raku. Soluable. Toxic.
F/A/G
Cornwall Stone (Cornish Stone)
A very comlex feldspathic material from England with many trace elements
making a generalized formula impossible. It is used in clay bodies giving
strengh while firing. Also used in engobes for its adhesive power during and
after firing. Used in glazes for its low shrinkage and minimal defects. From
England.
F
Cryolite-Na3AIF6
Can be used as a source of insoluble soda flux but fluorine may bubble
through glaze causing pinholes. Alumina content will tend to matt glaze
surface. In small percentages, may be used as a flux in low temperature clay
bodies.
F
Dolomite-CaMg(CO3)2
A calcium-magnesium mineral used primarily in high temperature glazes as a
flux. May be used to replace whiting to create matt effects and a buttery
finish in crystal formations. See Magnesium Carbonate and Talc.
F/A/G
Feldspars
Feldspars are a clay-type material but with much higher flux content. They
are the most common mineral of the Earth's crust. At high temperature, they
will fuse to form glass without additions. They are the main flux used in
mid-range and high fire clay bodies and are perhaps the most important
material in glazes of the same firing range. They are naturally occuring,
which means they are not pure but contain varying amounts of many minerals.
Generally, they are catagorized as Potash (primarily flux is potassium) or
Soda (primary flux is Sodium). Technically, they are further defined by
their crystal structure but in ceramics we often include Cornwall Stone,
Nepheline Syenite, petalite, spodumene and lepidolite as feldspars in that
they fundamentally function similarly in glaze formulations. When not
specified, potash feldspar is normally meant to be used.
Custer-A potash feldspar generally used when a specific feldspar is not
named. Potasium is the primary fluxing constituent.
Kona F-4 -A soda feldspar. Sodium is the primary fluxing agent which can
intensify colors. A somewhat stronger flux than custer.
F/
Fluorspar-CaF2
A substitute for whiting, assisting fusion. Also used as an opacifier.
Produces fluorine gas (toxic) when fired which can harm kiln interiors. Can
cause some blistering. Toxic.
Frits-see Frits section for details
F/G
Gerstley Borate-2CaO 3B2O3 5H2O
Often used interchangeably with colemanite which is no longer available. A
low temperature flux which helps to prevent crazing in glazes and acts
somewhat as an opacifier. Often gives an opalescent quality and can give a
mottled surface. Can be used as a substitute for calcium in glazes where a
pink or red tint is desired or where calcium would harm colors. It can cause
settling problems in the glaze bucket (add very small amounts of a
deflocculant, soda ash, Darvan or sodium silicate. Also see Borax)
Grogs
A relatively large particle sized material that does not melt and is added
to clay bodies to provide strength and workability while reducing shrinkage
and warping. Generally a fired clay that is crushed and graded by size. All
include fines.
Gums
Organic materials used as binders, thickeners and suspending agents in
glazes.
C
Ilmenite-Fe2O3 TiO2
Used in granular form to produce gold to brown speckles in glazes. A source
of iron and titanium similar to rutile. Grades vary batch to batch.
C/
Iron Chromate-FeCrO4
A darkening agent (dark gray and brown) in underglazes and engobes and in
combination with stains in clay bodies. In a tin glaze in oxidation, it can
develop a pink haze around the grey. It may also produce a blue-green in
high boron glazes. Toxic.
C/
Iron Chloride-FeCl36H2O
(Ferric Chloride) A hydroscopic, water soluble material used to produce
lusters in raku and in the glass industry. Toxic in raw form.
C
Iron Oxide, Red-Fe2O3
(Ferric Oxide) Used as a glaze colorant or decorative oxide. Can produce
browns, buffs and brick reds depending on concentration, formula and firing
variations. Blues or greens are possible in reduction. A flux in higher
concentrations, especially in reduction firings.
C
Iron Oxide, Black-Fe3O4
(Ferrous Oxide) When used as a decorative oxide or glaze colorant, yields a
variety of greens or browns similar to red iron but more concentrated.
C
Iron Sulphate-FeSO4
(copperas) A soluble colorant that can be mixed with water and applied to
produce red and violet lusterous effects, expecially in Raku. Soluable.
F
Lithium Carbonate-Li2CO3
Used as a flux in leadless glazes. It is a source of lithia,which is a
strong high temperature flux. Improves the brightness of glazes and
increases the firing range. Also reduces thermal expansion and promotes
crystallization.
F
Macaloid
A brand name for a beneficiated bentonite. In suspended glazes, lessons
drying time. Use 1/2 to 2 %.
F
Magnesium Carbonate- MgCO3
A high temperature flux imparts strength and produces a smooth, buttery matt
finish with little shrinkage. In higher quantities can produce a dry, opaque
finish. In lowfire is refractory and may make glaze cloudy with sugary matte
finish. It strongly affects colors, especially cobalt (more purple/violet).
F
Magnesium Sulfate-MgSO4
(Epsom Salts) Used in small proportions, it thickens (flocculates) glazes
without becoming lumpy, so they adhere better to a nonporous surface. Also
acts as a suspending agent. Soluble.
C
Magnetite Granular-Fe3O4
(Ferrous Oxide) A mineral form of black iron oxide. When mixed into clay
bodies or glazes, it produces a speckling effect. Recommended as a
substitute for ilmenite. Grades vary batch to batch.
C/
Manganese Carbonate-MnCO3
A weak coloring oxide. In an alkaline or barium glaze, it results in a
blue-purple color. In leaded glazes, a purple tinged with brown is produced.
In high temperature magnesium glazes, fawn, beige and pinkish-brown may also
be produced. Used alone and painted on bare clay it will form a matt to
gloss, dark brown to black surface in high fire. Mixed with an equal amount
of copper, it can produce bronze to gold surfaces and some crystalline
formulations. Can cause bubbles or pin-holing with release of gas. Is a
powerful flux. Toxic in large quantities of the raw forn
C
Manganese Dioxide -MnO2
See Manganese Carbonate-all are toxic
Powdered - A stable oxide giving red, brown, purple and black tones to clay
and glazes.
Granular - Same as the powdered form but larger particles produce spots.
Avoid prolonged inhalation.
F/A/G
Nepheline Syenite-K2O 3Na2O 4Al2O3 9SiO2
A high alumina-soda flux with some potash. Usually used in formulas for
medium to high range fluxing (cones 4-8). Results in a narrower firing range
than other feldspars. May be used in clay bodies to reduce crazing
tendencies in the glaze (i.e. increases vitrification of the clay).
O
Tin Oxide-SnO2
The most effective opacifier to produce even, opaque, glossy glazes. The
normal use of tin oxide in a glaze is between 5% and 10%. A dull matt glaze
can result when used in excess. Brightens some colors.
O
Titanium Dioxide-TiO2
In a glaze produces a semi-matt surface. A major opacifier, it may tend to
produce a cream color in some glazes. Also use as an agent in crystalline
glazes. See Rutile.
C
Umber, Burnt
A calcined earthen material used to color clays, slip and glazes a redish
brown. Contains clay, manganese and iron. Varies from batch to batch.
C/F
Vanadium Pentoxide-V2O5
A glaze colorant, it yields light yellow when used alone; with tin-bright
yellow; reduced-blue-gray, with Zirconium-blues. An active flux, it is water
soluble. Wear gloves.
F/G
Wollastonite-CaSiO2
Reduces shrinkage in clays and glazes. A source of calcium. Can replace
silica and whiting to reduce firing shrinkage and increase thermal shock
resistance in bodies and glazes.
F/O
Zinc Oxide -ZnO
A high temperature glaze flux in small amounts. Gives some opacity and
extends the maturation point producing mattness in large amounts. Can
produce bright, glossy colors but also may make colors more pastel in larger
amounts. Turns chrome brown, cobalt blue-grey, iron muddy yellow.
F/O
Zinc Sulphate
A soluble source of Zinc
O
Zircopax Plus-ZrSiO4
Slightly greater zircon content and finer grind than regular Zirocopax,
making it a very effective glaze opacifier. Replaces regular Zircopax which
is no longer available.


GLAZE MATERIALS
Glaze Materials Coding:
Preceding each material are letters representing their primary function in a
glaze, in descending order of their functional impact.
F = Flux
A = Alumina (refractory)
G = Glassformer
C = Colorant
O = Opacifier
= Toxic
A
Alumina Hydrate-Al2O3 3H2O
Occassionally used directly in glazes to increase hardness, viscosity and
stability. Also aids in craze resistance. Used in excess, it will tend to
give a matt surface. Most commonly used as a kiln wash, especially in
salt-glazing due to high refractory quality.
A
Alumina Oxide-Al2O3
(Calcined alumina hydrate) A refractory material contributing to a brilliant
or matte finish in glazes, depending on amount used. As with alumina
hydrate, normally alumina is introduced to glaze as a constitutent in clay
or feldspar.
C/G/O/
Antimony Oxide-Sb2O3
An opacifier for low fire glazes. Also used as a colorant producing yellow
to cream, stronger yellow with iron present. Toxic.
F/
Barium Carbonate-BaCO3
Used in glaze formulas as a flux at high temperatures. Produces frosty,
silky, soft matts. Makes colors more brilliant. Produces turqoise from
copper, yellow from iron, bright blue from cobalt. Also used in red clays
(2-3%) to help prevent soluble salt scum on the surface after firing.
Insoluble in water. Strontium Carbonate is sometimes used as a substitute.
The dust is toxic.
F/
Barium Sulfate-BaSO4
Used in some porcelain enamels to reduce shorelining and dimpling. See
Barium Carbonate for use in glazes. Toxic in raw form.
Clay
Bentonite-Al2O3 4SiO2 9H2O
A fine-grained clay that is quite sticky, very plastic with a very high
shrinkage. It swells considerably when wet and should be mixed with water
before introduced to a clay or glaze. Used in small percentages (1-3%) in
body plasticity and glaze suspension.
F/O
Bone Ash-Ca3(PO4)2
(Calcium Phosphate) Originally made of ground calcined animal bone; used in
bone china (up to 50%) to aid body translucency and strength. A flux and
opacifier in glazes. May render surface texture in some low-fire glazes.
Calcium Phosphate is the version normally used since it contains less
contaminates.
F/G
Borax-Pdr-Na2O 2B2O310H2O
Used in glaze formulas as a low temperature flux in lieu of lead, but is a
strong flux at all temperatures. Usually needs to be used in conjunction
with 2-4 other fluxes. Brightens colors. Often produces milky blue
opalescence, cloudy and spotted coloration. Very soluble in water, most
often used in a stable fritted form.
C/
Cadmium Oxide-CdO
Used to produce yellows, oranges and reds in low fire glazes. Very toxic in
raw form and prone to leaching from fired glaze.
F
Calcium Carbonote-CaCO3
(Whiting) A source of calcia in glazes. Used as a high temperature flux and
as a matting agent at lower temperatures. It produces a hard, durable glass
and renders a glaze less viscous in its molten state which can reduce
pin-holing.
Calcium Chloride-CaCl2
A flocculant used in very small amounts to keep particles in suspension.
Soluable.
F/O
Cerium Oxide-CeO2
An opacifier at low temperatures. Gives yellow when used with titania.
C/
Chromium Oxide, Green-Cr2O
A refractory ceramic color. Used with tin to produce pinks or with zinc for
browns. Extermely potent colorant. Very little is required to produce strong
greens in clays or glazes. Volatile when fired over cone 7. May affect the
color of adjacent ware in the kiln. Toxic.
Clays-Al2O3 2SiO2 2H2O
Used in glazes to help the glaze fuse to the body and help keeep the
ingredients suspended. A common source of alumina and silica in glazes. See
Clays-Raw section for details.
C/F/
Cobalt Carbonate-CoCO3
A very potent pigment, producing blue colors. Color variations: in lead
glazes, pale to dark inky blue; in barium, strontium and alkaline glazes,
brillian ultramarine blues; in magnesium glazes, pink lilac and purple blue;
in zinc glazes, soft grey blue. A very potent pigment, producing blue
colors. Best source of cobalt for glazes due to fine particle size. Toxic.
C/F/
Cobalt Oxide-CoO
A glaze colorant that produces reliable strong blue hues. Used in brushed
oxide decoration. Stronger and grainier than cobalt carbonate. Dark
blue-black in powder form. Toxic.
C/F/
Cobalt Sulfate-CoSO4
A water-soluble cobalt used in lustrous blues in raku firings. Neutralizes
yellow color of white slips. Soluable. Toxic.


C/
Copper Carbonate-CuCo3
A light green/ turquoise color in powder form. Very sensitive to temperature
and atmosphere to produce colors from red (good reduction in a soda base) to
turquoise, blue-green or purple in barium and alkaline glazes, to orange,
pink or grays in magnesium glazes, to metallic copper (raku). All coppers
are strong fluxes. The carbonate decomposes in hot water. Toxic.
C/
Copper Oxide-Black-CuO
(Cupric) Black dry color. Normally used wherever copper oxide is called for
and red or black is not specified. Copper tends to volatize somewhat at high
temperatures affecting adjacent colors. Toxic.
C/
Copper Oxide-Red-Cu20
(Cuprous) A concentrated copper form. Reverts to CuO in oxidation. Toxic.
C/
Copper Sulfate-CuSO4
A blue powder used to obtain greens and reds depending on firing atmosphere
and accompanying chemical in glaze, especially in Raku. Soluable. Toxic.
F/A/G
Cornwall Stone (Cornish Stone)
A very comlex feldspathic material from England with many trace elements
making a generalized formula impossible. It is used in clay bodies giving
strengh while firing. Also used in engobes for its adhesive power during and
after firing. Used in glazes for its low shrinkage and minimal defects. From
England.
F
Cryolite-Na3AIF6
Can be used as a source of insoluble soda flux but fluorine may bubble
through glaze causing pinholes. Alumina content will tend to matt glaze
surface. In small percentages, may be used as a flux in low temperature clay
bodies.
F
Dolomite-CaMg(CO3)2
A calcium-magnesium mineral used primarily in high temperature glazes as a
flux. May be used to replace whiting to create matt effects and a buttery
finish in crystal formations. See Magnesium Carbonate and Talc.
F/A/G
Feldspars
Feldspars are a clay-type material but with much higher flux content. They
are the most common mineral of the Earth's crust. At high temperature, they
will fuse to form glass without additions. They are the main flux used in
mid-range and high fire clay bodies and are perhaps the most important
material in glazes of the same firing range. They are naturally occuring,
which means they are not pure but contain varying amounts of many minerals.
Generally, they are catagorized as Potash (primarily flux is potassium) or
Soda (primary flux is Sodium). Technically, they are further defined by
their crystal structure but in ceramics we often include Cornwall Stone,
Nepheline Syenite, petalite, spodumene and lepidolite as feldspars in that
they fundamentally function similarly in glaze formulations. When not
specified, potash feldspar is normally meant to be used.
Custer-A potash feldspar generally used when a specific feldspar is not
named. Potasium is the primary fluxing constituent.
Kona F-4 -A soda feldspar. Sodium is the primary fluxing agent which can
intensify colors. A somewhat stronger flux than custer.
F/
Fluorspar-CaF2
A substitute for whiting, assisting fusion. Also used as an opacifier.
Produces fluorine gas (toxic) when fired which can harm kiln interiors. Can
cause some blistering. Toxic.
Frits-see Frits section for details
F/G
Gerstley Borate-2CaO 3B2O3 5H2O
Often used interchangeably with colemanite which is no longer available. A
low temperature flux which helps to prevent crazing in glazes and acts
somewhat as an opacifier. Often gives an opalescent quality and can give a
mottled surface. Can be used as a substitute for calcium in glazes where a
pink or red tint is desired or where calcium would harm colors. It can cause
settling problems in the glaze bucket (add very small amounts of a
deflocculant, soda ash, Darvan or sodium silicate. Also see Borax)
Grogs
A relatively large particle sized material that does not melt and is added
to clay bodies to provide strength and workability while reducing shrinkage
and warping. Generally a fired clay that is crushed and graded by size. All
include fines.
Gums
Organic materials used as binders, thickeners and suspending agents in
glazes.
C
Ilmenite-Fe2O3 TiO2
Used in granular form to produce gold to brown speckles in glazes. A source
of iron and titanium similar to rutile. Grades vary batch to batch.
C/
Iron Chromate-FeCrO4
A darkening agent (dark gray and brown) in underglazes and engobes and in
combination with stains in clay bodies. In a tin glaze in oxidation, it can
develop a pink haze around the grey. It may also produce a blue-green in
high boron glazes. Toxic.
C/
Iron Chloride-FeCl36H2O
(Ferric Chloride) A hydroscopic, water soluble material used to produce
lusters in raku and in the glass industry. Toxic in raw form.
C
Iron Oxide, Red-Fe2O3
(Ferric Oxide) Used as a glaze colorant or decorative oxide. Can produce
browns, buffs and brick reds depending on concentration, formula and firing
variations. Blues or greens are possible in reduction. A flux in higher
concentrations, especially in reduction firings.
C
Iron Oxide, Black-Fe3O4
(Ferrous Oxide) When used as a decorative oxide or glaze colorant, yields a
variety of greens or browns similar to red iron but more concentrated.
C
Iron Sulphate-FeSO4
(copperas) A soluble colorant that can be mixed with water and applied to
produce red and violet lusterous effects, expecially in Raku. Soluable.
F
Lithium Carbonate-Li2CO3
Used as a flux in leadless glazes. It is a source of lithia,which is a
strong high temperature flux. Improves the brightness of glazes and
increases the firing range. Also reduces thermal expansion and promotes
crystallization.
F
Macaloid
A brand name for a beneficiated bentonite. In suspended glazes, lessons
drying time. Use 1/2 to 2 %.
F
Magnesium Carbonate- MgCO3
A high temperature flux imparts strength and produces a smooth, buttery matt
finish with little shrinkage. In higher quantities can produce a dry, opaque
finish. In lowfire is refractory and may make glaze cloudy with sugary matte
finish. It strongly affects colors, especially cobalt (more purple/violet).
F
Magnesium Sulfate-MgSO4
(Epsom Salts) Used in small proportions, it thickens (flocculates) glazes
without becoming lumpy, so they adhere better to a nonporous surface. Also
acts as a suspending agent. Soluble.
C
Magnetite Granular-Fe3O4
(Ferrous Oxide) A mineral form of black iron oxide. When mixed into clay
bodies or glazes, it produces a speckling effect. Recommended as a
substitute for ilmenite. Grades vary batch to batch.
C/
Manganese Carbonate-MnCO3
A weak coloring oxide. In an alkaline or barium glaze, it results in a
blue-purple color. In leaded glazes, a purple tinged with brown is produced.
In high temperature magnesium glazes, fawn, beige and pinkish-brown may also
be produced. Used alone and painted on bare clay it will form a matt to
gloss, dark brown to black surface in high fire. Mixed with an equal amount
of copper, it can produce bronze to gold surfaces and some crystalline
formulations. Can cause bubbles or pin-holing with release of gas. Is a
powerful flux. Toxic in large quantities of the raw forn
C
Manganese Dioxide -MnO2
See Manganese Carbonate-all are toxic
Powdered - A stable oxide giving red, brown, purple and black tones to clay
and glazes.
Granular - Same as the powdered form but larger particles produce spots.
Avoid prolonged inhalation.
F/A/G
Nepheline Syenite-K2O 3Na2O 4Al2O3 9SiO2
A high alumina-soda flux with some potash. Usually used in formulas for
medium to high range fluxing (cones 4-8). Results in a narrower firing range
than other feldspars. May be used in clay bodies to reduce crazing
tendencies in the glaze (i.e. increases vitrification of the clay).
O
Tin Oxide-SnO2
The most effective opacifier to produce even, opaque, glossy glazes. The
normal use of tin oxide in a glaze is between 5% and 10%. A dull matt glaze
can result when used in excess. Brightens some colors.
O
Titanium Dioxide-TiO2
In a glaze produces a semi-matt surface. A major opacifier, it may tend to
produce a cream color in some glazes. Also use as an agent in crystalline
glazes. See Rutile.
C
Umber, Burnt
A calcined earthen material used to color clays, slip and glazes a redish
brown. Contains clay, manganese and iron. Varies from batch to batch.
C/F
Vanadium Pentoxide-V2O5
A glaze colorant, it yields light yellow when used alone; with tin-bright
yellow; reduced-blue-gray, with Zirconium-blues. An active flux, it is water
soluble. Wear gloves.
F/G
Wollastonite-CaSiO2
Reduces shrinkage in clays and glazes. A source of calcium. Can replace
silica and whiting to reduce firing shrinkage and increase thermal shock
resistance in bodies and glazes.
F/O
Zinc Oxide -ZnO
A high temperature glaze flux in small amounts. Gives some opacity and
extends the maturation point producing mattness in large amounts. Can
produce bright, glossy colors but also may make colors more pastel in larger
amounts. Turns chrome brown, cobalt blue-grey, iron muddy yellow.
F/O
Zinc Sulphate
A soluble source of Zinc
O
Zircopax Plus-ZrSiO4
Slightly greater zircon content and finer grind than regular Zirocopax,
making it a very effective glaze opacifier. Replaces regular Zircopax which
is no longer available.

Thanks for all the great suggestions and resources!