|Monthly Tech-Tip |
All common traditional ceramic base glazes are made from only a dozen elements (plus oxygen). Materials decompose when glazes melt, sourcing these elements in oxide form. The kiln builds the glaze from these, it does not care what material sources what oxide (assuming, of course, that all materials do melt or dissolve completely into the melt to release those oxides). Each of these oxides contributes specific properties to the glass. So, you can look at a formula and make a good prediction of the properties of the fired glaze. And know what specific oxide to increase or decrease to move a property in a given direction (e.g. melting behavior, hardness, durability, thermal expansion, color, gloss, crystallization). And know about how they interact (affecting each other). This is powerful. And it is simpler than looking at glazes as recipes of hundreds of different materials (each sources multiple oxides so adjusting it affects multiple properties).
Glaze chemistry is the study of how the oxide chemistry of glazes relates to the way they fire. It accounts for color, surface, hardness, texturem, melting temperature, thermal expansion, etc.
In glaze chemistry, the oxide is the basic unit of formulas and analyses. Knowledge of what materials supply an oxide and of how it affects the fired glass or glaze is a key to control.
In ceramics, the chemistry of fired glazes is expressed as an oxide formula. There are direct links between the oxide chemistry and the fired physical properties.
In ceramic manufacture, knowing about the how and when materials decompose during firing is important in production troubleshooting and optimization
|Oxides||Na2O - Sodium Oxide, Soda|
|Oxides||MgO - Magnesium Oxide, Magnesia|
|Oxides||SrO - Strontium Oxide, Strontia|
|Oxides||ZrO - Zirconium Oxide, Zirconia|
|Oxides||MnO - Manganous Oxide|
|Oxides||MnO2 - Manganese Dioxide|
|Oxides||V2O5 - Vanadium Pentoxide|
|Oxides||CrO3 - Chromium Trioxide|
|Oxides||Fe2O3 - Iron Oxide, Ferric Oxide|
|Oxides||FeO - Ferrous Oxide|
|Oxides||NiO - Nickel Oxide|
|Oxides||SnO2 - Tin Oxide, Stannic Oxide|
|Oxides||ZnO - Zinc Oxide|
|Oxides||PbO - Lead Oxide|
|Oxides||KNaO - Potassium/Sodium Oxides|
|Oxides||Li2O - Lithium Oxide, Lithia|
|Oxides||Al2O3 - Aluminum Oxide, Alumina|
|Oxides||B2O3 - Boric Oxide|
|Oxides||BaO - Barium Oxide, Baria|
|Oxides||Bi2O3 - Bismuth Oxide|
|Oxides||CaO - Calcium Oxide, Calcia|
|Oxides||CoO - Cobalt Oxide|
|Oxides||Cr2O3 - Chrome Oxide|
|Oxides||Cu2O - Cuprous Oxide|
|Oxides||CuO - Cupric Oxide|
|Oxides||SiO2 - Silicon Dioxide, Silica|
|Oxides||TiO2 - Titanium Dioxide, Titania|
|Oxides||ZrO2 - Zirconium Dioxide|
Glaze Chemistry Basics - Formula, Analysis, Mole%, Unity, LOI
Part of changing your viewpoint of glazes, from a collection of materials to a collection of oxides, is learning what a formula and analysis are, how conversion between the two is done and how unity and LOI impact this.
Understanding Ceramic Oxides
Fired glazes are composed of oxide building blocks. Each of the oxides contributes different properties to the fired glaze and interacts with others in different ways. Understanding these gives you control.
Changing Our View of Glazes
A big secret to getting control of glazes is to begin looking at them as formulas of oxides rather than recipes of materials.