Technical Tuesday: What is a Flux?
- , by Haley Stanaford
- 2 min reading time
What is a flux? And why is it mentioned so much? Fluxes are one of the integral parts to any glaze recipe, alongside glass formers and clays. Fluxes are the “melters” in the glaze, encouraging the mixture to melt at temperature. The higher the amount of flux in a recipe, the higher the melt and ability to melt at lower temperatures. But, they are not just melters.
Fluxes are made of Alkali and Alkaline Earth metals, which are celebrities on the Periodic Table of Elements. These elements appear to us in oxide compounds, which make up some raw materials.
A good balance of fluxes is what provides strength and durability to your glazed wares. A ratio of 0.3:0.7 Alkali to Alkaline Earth Metals (commonly written as R20:RO) is a strong, durable glaze. A ratio of 0.5:0.5 is sometimes used to lower the temperature needed to melt the glaze, but ends up creating a glaze that is not as durable. Matt Katz talks more in depth about that concept in this wonderful article from the 2016 NCECA journal.
So how do you view these numbers? Well, in the UMF of course! The UMF is the unified molecular formula which requires a lot of math to figure out, but can now be accessed way easier with the help of the internet! Glazy.org/calculator is a great, accessible UMF calculator! You can put in your recipe and see your UMF numbers in seconds. Thank you, technology and thank you, Glazy!
I put in the recipe for a classic 4-3-2-1 Glaze for Cone 10 that comes out clear. The red circle with the arrow pointing at it is where your flux ratio can be found in this calculator. This glaze has a R20:RO ratio of 0.29:0.71 which is super close to the desired 0.3:0.7!
Haley Stanaford is currently a Post Baccalaureate student in ceramics at the University of Kansas where she is currently taking a Clay and Glaze Formulation taught by Colby Charpentier in addition to her studio practice. She also is a Sales Representative at Bracker’s Good Earth Clays in Lawrence, Kansas.
