Glazing Review Basic Glaze Chemistry

What is in a glaze? 1. Flux - any ingredient that is used to help melt the glaze or to lower the temperature that the glaze will melt at. Commonly used fluxes: Limestone, gerstley borate, dolomite, lithium carbonate 2. Stabilizer - any ingredient that is used to extend the melting range of a glaze and to stiffen the glaze. Commonly used stablizers: Kaolin (china clay), Alumina

What’s in a glaze continued.. 3. Glass former - the main ingredient of a glaze. Silica is the main glass former. 4. Colorant - add color to the base glaze and are used in small amounts, they are usually metals like copper. Common colorants: copper carbonate, cobalt cabonate, iron oxide, rutile

Opacity Transparent Translucent Opaque Completely see through, clear Light can be seen through it, but is not transparent Opaque Solid, glaze completely covers color of clay, no light passes through

Types of Firings we do: Oxidation Reduction a firing during which the kiln chamber retains an ample supply of oxygen. An electric kiln always gives an oxidizing fire Bisque and low fire glazes Reduction a firing using insufficient oxygen; carbon monoxide thus formed unites with oxygen from the clay and glaze to form carbon dioxide, which produces color changes in the glazes

Pyrometric Cones Cones are specially designed to bend at specific times during a firing High Fire Cone 10 ~2350ºF Bisque and low fire glaze cone 06 ~1860ºF

Low-Fire Glaze (1860ºF) In small plastic containers Brush it on from different angles 2-3 coats

High-Fire In the buckets Glassy Food-safe Use tongs to dip Wipe off bottom!!!

How to High-Fire glaze Stir up glaze for 30 sec Blow dust off project Hold with tongs Dip in glaze for 2 seconds Don’t touch when wet

DO NOT attempt to glaze over fingers!!!!!!! Projects with fingerprints will be REJECTED and must be washed off and re-glazed Please use tongs

Glaze drips downward When it’s a hot liquid, it drips downward Wipe up about 1/2 an inch up the side

Put it back on the shelf to dry If you mess up…its OK! Wash it off in the sink Put it back on the shelf to dry Try again tomorrow!

Crawling The separation of a glaze coating from the clay caused by too heavy application, or glazing a dusty or dirty pot This results in exposed areas of unglazed clay.

Dry foot to clean the bottom of a glazed piece before firing

Wax Resist a method of decorating pottery by brushing on a design with a hot melted wax emulsion this will prevent an applied stain or glaze from adhering to the decorated portions

Wax Resist Paint on wax resist where you do not want glaze (bottom and ½ inch up side) Be careful not to drip Allow to fully dry before dipping Double check base for glaze droplets

Happy Glazing!