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Micrograph of phase separation in a glaze
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Example of serious glaze shivering using G1215U low expansion glaze on a high silica body at cone 6.
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The variegating effect of a thin layer of titanium dioxide (outside of bowl) on GA6-D Alberta Slip glaze at cone 6
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Amazing mold (actually sprouting leaves) that has grown on pugged clay after 10 months of storage where there is sunlight.
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Cone 10R dolomite matte glaze with 5% manganese dioxide
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Salt glazed vase
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Mold that has grown on pugged clay in a bag.
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Example of variegation and phase separation with about 5% rutile added to a dolomite matte cone 10R glaze.
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Crystallization in a high MgO matte at cone 10R
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Crystallization of rutile is completely subdued using Ferro frit 3249 (20% with Alberta Slip) on the right (the left is frit 3134 20%)
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Example of variegation and phase separation with about 5% rutile added to a dolomite matte cone 10R glaze.
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Plainsman P580, P600, H570 soda fired samples
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Woodash glaze cone 6 vase
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Bamboo glaze made by adding 4% tin and 0.5 and 1% iron oxide to G2571A at cone 10R
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2,3,4,5% rutile added to a 80:20 mix of Alberta Slip and Frit 3134 at cone 6
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A cone 10 reduction stoneware clay containing iron stone concretions ground to 20 mesh
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A wood ash glaze at cone 6
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This high boron cone 04 glaze is generating calcium-borate crystals during cool down
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Example of crazing in a glaze
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Alberta Slip used as a straight glaze at cone 10R, it looks much like a Tenmoku.
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A cone 10 reduction tenmoku glaze with about 10% iron oxide.
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Cone 10 reduction fired crystallizing kaki glaze (about 12% iron oxide).
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Celadon cone 10R glaze (about 3.5% iron oxide) with G1947U transparent liner glaze
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Example of a crystalline glaze
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Example of variegation and phase separation with about 5% rutile added to a dolomite matte cone 10R glaze.
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Cone 6 GA6-C variegated blue showing different thicknesses (4% rutile+ 20% frit 3134 in Alberta Slip)
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This high boron cone 04 glaze is generating calcium-borate crystals during cool down
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Example of variegation and phase separation with about 5% rutile added to a dolomite matte cone 10R glaze.
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Example of a variegated wood ash glaze at cone 6 oxidation.
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Example of a variegated wood ash glaze at cone 6 oxidation.
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The top bar is a mix of calcium carbonate and clay fired to cone 6. The bottom is a couple of minutes after water was poured onto it.
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An example of the effects of reduction firing on two clays with the same glaze, one is a iron brown body, the other a grey stoneware.
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Copper red reduction glaze cone 9 courtesy of Angela Walford
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Crystallization in a high MgO matte at cone 10R
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Brown and buff stoneware clays compared to a porcelain at 1300C in reduction. Courtesy of Plainsman Clays.
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Brown and buff stoneware clays compared to a porcelain at 1300C in reduction. Courtesy of Plainsman Clays.
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This is what about 8% iron can do in a transparent base glaze with slow cooling at cone 10R on a refined porcelain.
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Example of a terra cotta clay fired at cone 04 and cone 02. Courtesy of Plainsman Clays.
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Example of a grogged cone 10 reduction vitreous and non vitreous iron speckled sculpture clay.
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Classic dolomite glaze at cone 10 reduction on a speckle producing clay body (10R). The magnesia flux in dolomite creates a silky matte surface.
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Cone 10R dolomite matte glaze with 5% manganese dioxide
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crystalline and vitreous silica matrix
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Example of a crystalline glaze
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This high boron cone 04 glaze is generating calcium-borate crystals during cool down
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Fired test bars of a terra cotta clay showing varying levels of maturity or vitrification, DFAC disk showing solubles on an iron stoneware
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A variegated glossy blue ravenscrag slip glaze
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Fired test bars of a terra cotta clay showing varying levels of maturity or vitrification, DFAC disk showing solubles on an iron stoneware
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Fluid rutile glaze
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Wood fired test samples. Made in the Medalta kiln in Medicine Hat, Alberta, Canada.
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Flashing effect on a cone 10 wood fired sample.
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Cone plaques and cones from a cone 10R firing at Plainsman Clays.
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Various different cone fired 10R clays with soluble salts on the surface
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2571A base glaze with 4% tin and 0.5 and 1.0% iron oxide to create a bamboo matte
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Simple propeller mixer with mount and switch (this 1/3 hp mixer can handle up to 10 gallons).
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Example of how a frit softens over a wide temperature range
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This one inch tall mug fired at cone 5 with Alberta Slip+20% frit 3134 is similar to a cone 10 reduction celadon glaze.
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Simple propeller mixer with mount and switch (this 1/3 hp mixer can handle up to 10 gallons).
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Scale, calipers and fired test bars to be measured for shrinkage
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DFAC dried disk showing soluble salts and drying performance crack typical of a plastic pottery clay body.
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Drying disks used for the DFAC test to measure the drying performance of a clay
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DFAC dried disk showing soluble salts and drying performance crack typical of a plastic pottery clay body.
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Dialometric thermal expansion chart
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Examples of various sized grogs from CE Minerals, Christy Minerals, Plainsman Clays
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Flow tester demonstrates how zircon opacifys and stiffens a glaze melt
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1215U flow test, MgO is sourced from Talc (right) and from a much more actively melting MgO frit (left).
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Example of how a frit softens over a wide temperature range
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Example of a tenmoku on a white stoneware and a Grolleg porcelain.
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Tenmoku mug with throwing rings.
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DFAC dried disk showing soluble salts and drying performance crack typical of a plastic pottery clay body.
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Example of how simple placement of mugs during drying can prevent cracking of handles
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Bloating in an over fired terra cotta body. It is OK at cone 4 but suddenly bloating begins at cone 5.
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Flow tester demonstrates how zircon opacifys and stiffens a glaze melt
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Example of a cone 10 transparent that is running severely on a flow tester, but does run on actual ware. The glaze is cutlery marking (therefore lacking hardness). This, the running and likely leaching are due to extremely low SiO2, Al2O3 content.
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Example of a cone 10 transparent that is running severely on a flow tester, but does run on actual ware. The glaze is cutlery marking (therefore lacking hardness). This, the running and likely leaching are due to extremely low SiO2, Al2O3 content.
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Example of various materials mixed 75:25 with volclay 325 bentonite and fired to cone 9. Plasticities and dry shrinakge vary widely. Materials normally acting as fluxes are refractory.
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1215U flow test, MgO is sourced from Talc (right) and from a much more actively melting MgO frit (left).
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Metallic oxides with 50% Ferro frit 3134 in crucibles at cone 6ox. Chrome and rutile have not melted, copper and cobalt are extremely active melters. Cobalt and copper have crystallized during cooling, manganese has formed an iridescent glass.
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This is a metallic silky crystal black, it is Alberta Slip plus 5% black stain and 7% iron.
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Metallic deep purple by firing pure alberta slip at cone 10R, then refiring at cone 6 oxidation.
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Metallic oxides with 50% Ferro frit 3134 in crucibles at cone 6ox. Chrome and rutile have not melted, copper and cobalt are extremely active melters. Cobalt and copper have crystallized during cooling, manganese has formed an iridescent glass.
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Metallic oxides with 50% Ferro frit 3134 in crucibles at cone 6ox. Chrome and rutile have not melted, copper and cobalt are extremely active melters. Cobalt and copper have crystallized during cooling, manganese has formed an iridescent glass.
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Metallic oxides with 50% Ferro frit 3134 in crucibles at cone 6ox. Chrome and rutile have not melted, copper and cobalt are extremely active melters. Cobalt and copper have crystallized during cooling, manganese has formed an iridescent glass.
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Albany Slip DFAC dried disk showing the soluble salts and characteristic cracking pattern and cut edge of a low plasticity clay.
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Cone 11 flow test of original cornwall stone, H&G substitute 2011 and L3617 calculated equivalent
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Example of calcium carbonate (top) and dolomite (both mixed with 25% bentonite). They are fired to cone 9. Both bars are porous and refractory, even powdery.
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This 1000 ml 24 hour sedimentation test compares Plainsman A2 ball clay ground to 10 mesh (left) with one that same material ball milled (right). There is no sediment in the milled material.
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This 1000 ml 24 hour sedimentation test compares Plainsman A2 ball clay ground to 10 mesh (left) with one that same material ball milled (right). There is no sediment in the milled material.
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This 1000 ml 24 hour sedimentation test compares Plainsman A2 ball clay ground to 10 mesh (left) with one that same material ball milled (right). There is no sediment in the milled material.
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Ball mill rack front side
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Example of sedimentation test to compare soluble salts water extracts from suspended clay. This simple test also reveals ultimate particle size distribution differences in clays.
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Cone 10R firing of Plainsman FireRed (left), St. Rose Red 42 mesh (center) and St. Rose Red 10 mesh (right). The 10 mesh material produces a reduction speckle and deep red color that is very unique.
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Plainsman P580 (35:17:1.5 ball clay:kaolin:bentonite), H570 (10:46:2.5), P700 (50:5 Grolleg:bentonite) and Crysanthos Porcelain (China) fired in oxidation at cone 10.
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