K2Cr2O7—Occasionally used as acid-green colorant in raku glazes, but is highly toxic in absorption, ingestion, and inhalation.
Source:
Clay: A Studio Handbook
Potash Feldspar
Materials like G-200; Custer feldspar.
Source:
Clay: A Studio Handbook
Portland Cement
Calcium silicate aluminate—air-setting cement, often added in small quantities to homemade castable refractor mix in order to introduce air-setting qualities. Toxic in inhalation.
Source:
Clay: A Studio Handbook
Porcelaneous
White-firing stoneware clay bodies closely related to porcelain.
Source:
Clay: A Studio Handbook
Porcelain
High-fired vitreous clay body containing kaolin, silica, fluxes, and often ball clay to increase plasticity, with total clay component not more than 50%. Usually pure white or “eggshell” in color; some porcelains may fire translucent where thin.
Source:
Clay: A Studio Handbook
Polishing
As compared to burnishing, the act of creating a shiny surface on terra sigillata (or any clay or slip) by rubbing with soft cloth, a soft brush, or a piece of plastic film.
Source:
Clay: A Studio Handbook
Platelets
Flat, thin crystals that make up clay. When wet they become sticky and slippery, creating the phenomenon we call plasticity.
Source:
Clay: A Studio Handbook
Plasticizers
Materials added to some clay bodies, especially those high in kaolins, to increase plasticity and dry strength—includes bentonite, Macaloid, Veegum-T.
Source:
Clay: A Studio Handbook
Plasticity
Quality of moldable flexibility in damp clay—superior plasticity depends on smaller clay particle size, slight acidity, less non-plastic additives, aging of damp clay body, adequate water content, and/or addition of accessory plasticizers, such as Veegum T or Macaloid.
Source:
Clay: A Studio Handbook
Plastic Vitrox
K2O/Na2O/CaO×Al2O3×10SiO2—a plastic high-potash feldspathic clay, similar in structure to Cornwall stone—used in place of potash feldspar in some porcelain bodies to increase plasticity. Toxic in inhalation.
Source:
Clay: A Studio Handbook
Pit Firing
A type of bonfire-firing where wares are buried in sawdust in a pit in the ground and a bonfire is built on top, so that the fire and coals slowly burn away the sawdust and fire the wares. Not to be confused with sawdust smoking.
Source:
Clay: A Studio Handbook
Pinholing
Glaze defect characterized by fine pinholes in the surface—often caused by pinholes already present in dry unfired glaze coating. Can also be caused by burst bubbles in glaze surface that are not given opportunity to “heal” at end of firing.
Source:
Clay: A Studio Handbook
Petuntse
Feldspathic rock, similar to Cornwall stone, found in China. Traditional Chinese flux for HT glazes and clay bodies.
Source:
Clay: A Studio Handbook
Petalite
Li2O×Al2O3×8SiO2—lithium feldspar—HT alkaline flux—good for reducing thermal expansion, increasing thermal-shock resistance. Toxic in inhalation.
Source:
Clay: A Studio Handbook
Perlite
Porous expanded granular silica, useful in making insulating refractories.
Source:
Clay: A Studio Handbook
Periodic Table Of The Elements
A table listing all of the chemical elements (those substances that can theoretically be reduced to individual atoms), with the smallest and simplest across the top and the heaviest and most complex at the bottom and grouped by similar physical/chemical characteristics.
Source:
Clay: A Studio Handbook
Patina
An overall thin wash of glaze or oxide stain, allowing the color and texture of the clay body to show through.
Source:
Clay: A Studio Handbook
Paper Resist
Decoration technique where strips of moist or adhesive paper are adhered to the surface to resist application of slip or glaze.
Source:
Clay: A Studio Handbook
Paper Clay
Technique popularized by Rosette Gault, utilizing a clay body or slip containing paper pulp, which reduces shrinkage in drying stage, and encourages extremely strong joinery, allowing unconventional joinery such as wet to dry.
Source:
Clay: A Studio Handbook
Oxidize
To subject a material to a high-oxygen atmosphere, encouraging oxidation reactions.
K2Cr2O7—Occasionally used as acid-green colorant in raku glazes, but is highly toxic in absorption, ingestion, and inhalation.
Source: Clay: A Studio Handbook
Materials like G-200; Custer feldspar.
Source: Clay: A Studio Handbook
Calcium silicate aluminate—air-setting cement, often added in small quantities to homemade castable refractor mix in order to introduce air-setting qualities. Toxic in inhalation.
Source: Clay: A Studio Handbook
White-firing stoneware clay bodies closely related to porcelain.
Source: Clay: A Studio Handbook
High-fired vitreous clay body containing kaolin, silica, fluxes, and often ball clay to increase plasticity, with total clay component not more than 50%. Usually pure white or “eggshell” in color; some porcelains may fire translucent where thin.
Source: Clay: A Studio Handbook
As compared to burnishing, the act of creating a shiny surface on terra sigillata (or any clay or slip) by rubbing with soft cloth, a soft brush, or a piece of plastic film.
Source: Clay: A Studio Handbook
Flat, thin crystals that make up clay. When wet they become sticky and slippery, creating the phenomenon we call plasticity.
Source: Clay: A Studio Handbook
Materials added to some clay bodies, especially those high in kaolins, to increase plasticity and dry strength—includes bentonite, Macaloid, Veegum-T.
Source: Clay: A Studio Handbook
Quality of moldable flexibility in damp clay—superior plasticity depends on smaller clay particle size, slight acidity, less non-plastic additives, aging of damp clay body, adequate water content, and/or addition of accessory plasticizers, such as Veegum T or Macaloid.
Source: Clay: A Studio Handbook
K2O/Na2O/CaO×Al2O3×10SiO2—a plastic high-potash feldspathic clay, similar in structure to Cornwall stone—used in place of potash feldspar in some porcelain bodies to increase plasticity. Toxic in inhalation.
Source: Clay: A Studio Handbook
A type of bonfire-firing where wares are buried in sawdust in a pit in the ground and a bonfire is built on top, so that the fire and coals slowly burn away the sawdust and fire the wares. Not to be confused with sawdust smoking.
Source: Clay: A Studio Handbook
Glaze defect characterized by fine pinholes in the surface—often caused by pinholes already present in dry unfired glaze coating. Can also be caused by burst bubbles in glaze surface that are not given opportunity to “heal” at end of firing.
Source: Clay: A Studio Handbook
Source: Clay: A Studio Handbook
Li2O×Al2O3×8SiO2—lithium feldspar—HT alkaline flux—good for reducing thermal expansion, increasing thermal-shock resistance. Toxic in inhalation.
Source: Clay: A Studio Handbook
Porous expanded granular silica, useful in making insulating refractories.
Source: Clay: A Studio Handbook
A table listing all of the chemical elements (those substances that can theoretically be reduced to individual atoms), with the smallest and simplest across the top and the heaviest and most complex at the bottom and grouped by similar physical/chemical characteristics.
Source: Clay: A Studio Handbook
An overall thin wash of glaze or oxide stain, allowing the color and texture of the clay body to show through.
Source: Clay: A Studio Handbook
Decoration technique where strips of moist or adhesive paper are adhered to the surface to resist application of slip or glaze.
Source: Clay: A Studio Handbook
Technique popularized by Rosette Gault, utilizing a clay body or slip containing paper pulp, which reduces shrinkage in drying stage, and encourages extremely strong joinery, allowing unconventional joinery such as wet to dry.
Source: Clay: A Studio Handbook
To subject a material to a high-oxygen atmosphere, encouraging oxidation reactions.
Source: Clay: A Studio Handbook