Ceramic Oxides OverviewCeramic formulation and adjustment technology can be approached on different levels: The oxide, the mineral, the material, the recipe and the process. If you want to understand what you are doing you first need to separate the problem into aspects that relate to each of these levels.
At the oxide level we study the relationships between the fired properties of glazes and their chemistry. Understanding what each of the oxides is bringing to the chemistry is one of the most important aspects to controlling glazes (on this level there are complicating factors of oxide interaction, issues relating to sourcing oxides from different materials, non-linear property changes with linear changes in proportion). Generally it is difficult to draw relationships between the chemistry of vitreous bodies and their physical fired properties. This is because bodies are not melted during firing as are glazes, normally firing creates conditions of crystal growth in the body. Thus bodies of similar chemistry can develop completely different crystalline matrixes and therefore different physical properties (depending on firing and mineralogy of ingredients).
Chemistry needs to be put in context with the other levels. For example, consider a glaze that is crazing: If it contains alot of Na2O3, then it has a high thermal expansion, that is almost certainly the cause. Glaze chemistry is needed to reduce the amount of sodium and substitute another flux of lower thermal expansion (which of course is also sympathetic to the glaze color, surface character, melting temperature, etc.). However if the glaze contains alot of nepheline syenite that is the material contributing the Na2O. To reduce it ceramic chemistry is needed to substitute in another sodium sourcing material. Doing this actually solves a material level issue, nepheline is slightly soluble and excessive amounts flocculate glazes (thus they require more water and then begin to settle out in the bucket). This is a mineral and process level issue.
Since many ceramic oxides have mineral and even material equivalents, it is logical that documentation be found on the proper level. For example, the oxide SiO2 is usually just called silica. The mineral quartz is SiO2 and it is a type of silica mineral. The powdered material silica that we use in recipes is also SiO2. For example, if the silica powder is being put into a glaze then it will impose a dramatic lowering effect, documentation about this belongs at the oxide chemistry level (in this area of the database). Discussion about the use of silica in bodies usually belongs on the material level since it is seen, not as an addition of chemistry, but as an aggregate, a filler and a source of glass. Theoretical information about the mineral quartz (e.g. its thermal expanion, hardness) and belong on the mineral level. Then, of course, there are normally many issues related to cost and supply, these belong on the material level. This site has a flexible linking system between all areas and records (which we regard as the most value aspect of the database) and we are constantly working on improving the links. See Also - The Four Levels on Which to View Ceramic Glazes
By knowing which level to view a glaze from you are much better equipped to understand and control it. The levels are process, recipe, material, oxide. - Ceramic 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, now conversion between the two is done and how unity and LOI impact this. - Chemistry vs. Matrix Blending to Create Glazes from Native Materials
Is it better to do trial and error line and matrix blending of materials to formulate your glazes or is it better to use ceramic chemistry? - 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. - Where Do I Start?
The perfect universal glaze recipe does not exist, the only way you will get the glazes you really need is formulate or adapt them yourself. Start with base recipes, learn to understand them from a material level, then learn the mechanisms, and chemistry. - Glaze Formula to Batch Calculations
This chapter in the lessons section of the book (and matching video at digitalfire.com) shows you how to use a non-unity calculation and the supply button to convert a formula into a batch recipe. You... - Ceramic Chemistry
There is a close link between the way glazes fire in a kiln and their chemistry. Physical properties like color, hardness, melting temperature, thermal expansion, leachability, etc are all direct products of the chemistry. Understanding the relationship between the absolute and relative amounts of t... - Oxide
An oxide is a molecule like K2O, Al2O3. They are the most basic form of matter that kiln temperatures can normally decompose materials into. Thus for calculation purposes we view fired glazes and ceramic materials as made of oxides. An oxide is a combination of oxygen and another element (designated... - Oxides and Materials in INSIGHT
The first chapter of the INSIGHT software manual shows the dialogs and tools that its uses to maintain a materials database. An INSIGHT materials database is conceptually composed of oxide columns and...
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