The Glaze Process
Projects 1-5 Glazed by December 11th,2015
Project 4-8 Glazed by April 22nd, 2016
Final Glazed by May 13th, 2016
Project 4-8 Glazed by April 22nd, 2016
Final Glazed by May 13th, 2016
Objective 1: Watch the glaze technique videos below. Take notes on how techniques are done & apply this to your designs.
Objective 2: Research (links on class website Sketch Assignments) & design surface decorations for your completed bisqueware.
Objective 2: Research (links on class website Sketch Assignments) & design surface decorations for your completed bisqueware.
Kiln-- an insulated box, which is heated to fire pottery in. They can be either, cross draft, down draft, or up draft. Since no combustion takes place in an electric kiln, there are no input or exit flues. The fuels used to heat a kiln are gas, oil, wood, coal (now almost obsolete) and electricity. Each fuel source used to fire a kiln offers different possible outcomes for the pottery fired in them. The maximum operating temperature for most pottery kilns is about 2372 F (1300 C) although many wood fired kilns may be fired up to 2462 F (1350 C).
Peep Hole-- kilns have two or three sections stacked on top of each other and each section has a one inch hole that has a removable ceramic plug that can be removed to check progress of firing by looking at cones.
Firing-- The process, which changes clay into ceramic. Up to 600oC / 1112 oF the chemically bonded water in clay is driven off (AL2O3 2SiO2 2H2O - AL2O3 2SiO2). This is an irreversible change know as the “Ceramic Change”,
Cones-- pyrometric cones are composed of clay and glaze material, designed to melt and bend at specific temperatures. Cones are a better indicator than temperature alone as the degree of glaze melt is a combination of time and temperature heat work.
Cone Numbers-- cones are numbered from cone 022 up to cone 12. Cone 022 is the lowest melting cone and requires the least amount of heat to deform or bend. During firing, a cone softens and melts as it is heated. This bending indicates the cone and the piece of pottery has received a specific amount of heat. It typically takes 15 to 22 minutes for cones to bend fully once they start bending. Each higher cone number requires more heat to bend. A cone 01 needs less heat treatment than cone 1 and cone 020 needs less than 019. Although cones do not actually measure temperature, cone bending behavior and temperature are related.
Oxidation-- Firing with a full supply of oxygen. Electric kilns fire in oxidation. Oxides show bright colors.
Reduction-- Firing with reduced oxygen in the kiln. Colors are darker and often produce varied and unique results.
Bisque--First firing to remove excess water & organic materials from greenware in preparation for glazing. Slips can be used in a bisque firing.
Bisqueware-- Ceramic object that has undergone the initial firing.
Glaze--A suspension consisting of flux, alumina, silica & colorants/ opacifiers to bisqueware for decoration & function. This also vitrifies the surface.
Firing:-- The process, which changes clay into ceramic. Up to 600oC / 1112 oF the chemically bonded water in clay is driven off (AL2O3 2SiO2 2H2O - AL2O3 2SiO2). This is an irreversible change know as the “Ceramic Change”.
Flux--A substance, which causes or promotes melting
Alumina-- (AL2O3) Aluminum oxide is a common, naturally occurring compound that’s employed in various industries, most particularly in the production of aluminum and industrial ceramics. Its most common crystalline form, corundum, has several gem-quality variants such as rubies and sapphires.
Sillica-- (2SiO2) The primary glass forming oxide used in pottery.
Oxide-- Any element combined with oxygen.
Colorant-- A mineral or any combination of minerals (iron,, copper, manganese, cobalt, etc) used to give a glaze color. Minerals in a glaze will achieve different colors in different firing atmospheres and at different temperatures. Copper for example may appear as red, black, pink, green or blue at different temperatures. Industrial stains may also be used to color a glaze as well. These are generally inert and achieve consistent results.
Opacifier--is a substance added to a material in order to make the ensuing system opaque. An example of a chemical opacifier is tin dioxide (SnO2).
Glazeware--Ceramic object that has been glazed and undergone a second or series of firings thereby removing chemically bound water and impurities adhering glaze to the surface.
Vitrification--The transformation of a surface into glass, thereby making it waterproof.
Peep Hole-- kilns have two or three sections stacked on top of each other and each section has a one inch hole that has a removable ceramic plug that can be removed to check progress of firing by looking at cones.
Firing-- The process, which changes clay into ceramic. Up to 600oC / 1112 oF the chemically bonded water in clay is driven off (AL2O3 2SiO2 2H2O - AL2O3 2SiO2). This is an irreversible change know as the “Ceramic Change”,
Cones-- pyrometric cones are composed of clay and glaze material, designed to melt and bend at specific temperatures. Cones are a better indicator than temperature alone as the degree of glaze melt is a combination of time and temperature heat work.
Cone Numbers-- cones are numbered from cone 022 up to cone 12. Cone 022 is the lowest melting cone and requires the least amount of heat to deform or bend. During firing, a cone softens and melts as it is heated. This bending indicates the cone and the piece of pottery has received a specific amount of heat. It typically takes 15 to 22 minutes for cones to bend fully once they start bending. Each higher cone number requires more heat to bend. A cone 01 needs less heat treatment than cone 1 and cone 020 needs less than 019. Although cones do not actually measure temperature, cone bending behavior and temperature are related.
Oxidation-- Firing with a full supply of oxygen. Electric kilns fire in oxidation. Oxides show bright colors.
Reduction-- Firing with reduced oxygen in the kiln. Colors are darker and often produce varied and unique results.
Bisque--First firing to remove excess water & organic materials from greenware in preparation for glazing. Slips can be used in a bisque firing.
Bisqueware-- Ceramic object that has undergone the initial firing.
Glaze--A suspension consisting of flux, alumina, silica & colorants/ opacifiers to bisqueware for decoration & function. This also vitrifies the surface.
Firing:-- The process, which changes clay into ceramic. Up to 600oC / 1112 oF the chemically bonded water in clay is driven off (AL2O3 2SiO2 2H2O - AL2O3 2SiO2). This is an irreversible change know as the “Ceramic Change”.
Flux--A substance, which causes or promotes melting
Alumina-- (AL2O3) Aluminum oxide is a common, naturally occurring compound that’s employed in various industries, most particularly in the production of aluminum and industrial ceramics. Its most common crystalline form, corundum, has several gem-quality variants such as rubies and sapphires.
Sillica-- (2SiO2) The primary glass forming oxide used in pottery.
Oxide-- Any element combined with oxygen.
Colorant-- A mineral or any combination of minerals (iron,, copper, manganese, cobalt, etc) used to give a glaze color. Minerals in a glaze will achieve different colors in different firing atmospheres and at different temperatures. Copper for example may appear as red, black, pink, green or blue at different temperatures. Industrial stains may also be used to color a glaze as well. These are generally inert and achieve consistent results.
Opacifier--is a substance added to a material in order to make the ensuing system opaque. An example of a chemical opacifier is tin dioxide (SnO2).
Glazeware--Ceramic object that has been glazed and undergone a second or series of firings thereby removing chemically bound water and impurities adhering glaze to the surface.
Vitrification--The transformation of a surface into glass, thereby making it waterproof.
Requirements:
- Surface decoration must use multiple layers of glaze & combine different techniques.
- Composition is key! Surface treatment must have flow through the entire object--inside and out. Objects will demonstrate use of varied line, shape, contrast, value, variety and unity.
- 5 sketches--one very week.
- Self-Assessment