When discussing how glazes work, there are three main elements of a glaze:
- The Glass Former
The Glass Former is the element that actually makes the glass (glaze) on the pot melt. The main Glass Former is known as Silica. Silica has a very high melting point of 3100 Degrees Fahrenheit.
Fluxes are chemicals used in glazes to help lower the temperature of the ‘melting point’. Most kilns don’t require a temperature of 3100 Degrees Fahrenheit to melt the glaze. For instance, most everything I fire is in the ^6 range (cone 6 = 2170 degrees Fahrenheit). In order for that to happen, I must use some flux in my glaze recipes to lower the reaction temp that the glass former requires. There is a down side to using flux in a glaze; the more flux amount used, the runnier the glaze becomes.
Refractories keep glaze from running off the pot. If you have a glaze that is too runny, you need to add more EPK (Kaolin) or Aluminum, which are both refractories.
I found a great short video that explains how all three of these properties work together. Each of the three, The Glass Former, the Flux, and Refractories cause changes to happen the other.
These three components make up what is called the “Base” or “Base Glaze”. After the Base has been configured, then the potter can begin working with color elements to see how each color element can create a different look. The “Color Theory” element of glazing is something we will hold off with right now because that could take several posts. Once you start adding/subtracting color chemicals you may have to change other components too to compensate for that adding/subtracting.
I sure hope this helps you understand a bit about glaze theory!