A property in this context is a created physical phenomenon in a glaze or body that can be achieved in a variety of ways (called mechanisms). For example, there are a number of ways to suspend a glaze slurry, a number of mechanisms of glaze opacify or body plasticity, a number of ways to achieve a specific glaze color, etc. Whether a mechanism is physical or chemical, we need to understand all the options to choose a suitable one for a specific application.
Consider an example: If we define 'glaze color' as a property, then we can attach a 'glaze color mechanism' to the oxide chrome, specify 'pink' as the detail and explain how the mechanism works. Likewise, to alumina oxide we can attach a glaze color property noting that with chrome, manganese, and cobalt it can achieve pink colors. Now if we search for the specific instance of pink in the glaze color property in this area we will find these two mechanisms listed. You will not fully appreciate the potential of this until you really need to produce a specific effect and this area makes you aware of a way to do it that you never considered or even thought existed.
Another example is opacification, most people are not aware of how many ways there are to opacify glazes. This area makes it easy to browse all the mechanisms, evaluate the tradeoffs and select the best one (or combination).
By Tony Hansen
- 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.
- Identifying Glaze Mechanisms
Identifying the mechanism of glazes from the recipe or visual inspection (what produces the color, opacity and variegation) is the key to moving adjusting it, moving it, reverse engineering it, even avoiding it!
- Variegating Glazes
This is an overview of the various mechanisms you can employ to make glazes dance with color, crystals, highlights, speckles, rivulets, etc.
- COE, Co-efficient of Thermal Expansion
A measure of the reversible volume or length change of a ceramic material with temperature. The more the expansion during heating the more contraction must occur while cooling it back down. Expansion values are very small and recorded in scientific notation (e.g. 6.5 x 10-7 which is 0.00000065). Typ...
Rheology refers to the array of characteristics that a ceramic slurry exhibits, its flow, thixotropy, etc. Technicians seek to understand and control the dynamics of the slurries they use to maintain consistency and optimize them for the product and process at hand. This is done by the control of wa...
This term is used in reference to clays (or more often bodies which are blends of clay, feldspar and silica particles) and their ability to assume a new shape without any tendency to return to the old (elasticity). Plasticity is a product of the electrolytic character of flat clay particles (they ha...
- Opacifier, Opacification
A glaze additive that transforms an otherwise transparent glaze into an opaque one. Common opacifiers are tin oxide and zircon compounds. Opacifiers typically work by simply not dissolving into the melt, the white suspended particles thus reflect and scatter the light. Since they do not participate ...
Vitrification is the solidification of a melt into a glass rather than a crystalline structure (crystallization). Glass, clay bodies and glazes vitrify, but in ceramics use of the term focuses most on clay bodies.
Vitrification is a process. As clay is fired hotter and hotter, it reaches a point ...
- Matte Glaze
A glaze that is not glossy. Of course, unmelted glazes will not be glossy, but to be a true matte a glaze must be melted and still not glossy. To be a functional matte it must also resist cultery marking, clean well and not leach into food and drink. Thus it is not easy to make a good matte glaze. I...
- Deflocculate, deflocculation, deflocculant
The process of making a clay slurry that would otherwise be very thick and gooey into a thin pourable consistency. It is the opposite of flocculation. Deflocculants are electrolytes liquids or powders (like sodium silicate, Darvan, Calgon) that are added in small amounts, they work their magic by im...