When we talk about converting a glaze from Cone 10 to cone 6, we need to have a precise understanding of our chemistry.
First we need to understand what materials we are using to get the temperature down. The majority of the time, the best option is Boron. We find this material in frits, but also in naturally occurring materials such as Gerstley Borate, and Colemanite.
How much Boron is also important. In this image we see 0.03 increases in Boron, via UMF. In our research (See NCECA Journal 2012) we have found that roughly 0.15 Boron is an ideal level for a ^6 Glaze. We have to be careful though as too much boron in this case kills the color. The color peaks at 0.19 and then as the glaze becomes increasingly overfired, the color begins to fade and turn brown.
If you want to learn more about how your glazes really work, join us for our next Session or Understanding Glazes, begging July 1st! Our in-depth study of how and why glazes work and how to make the most of them. It is the same course we teach as schools such at Alfred University, The Rhode Island School of Design and Harvard University! Open to makers all over the world, of all experience levels! All you need is an internet connection!
Also, We're having a follower drive and we need your help! We need to get to 10,000 Instagram followers so we're having a contest to help us get there.
To enter our contest, we need you to tag a friend in CMW posts made between now and July 1st. Then, make sure your friend follows us too.
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I've had a few conversions recently about glaze durability. Here is my article that I published in the 2016 NCECA journal on that subject.
I looked into the the question of why glazes are durable or not and found that we are able to correlate the overall durability of a glaze to its underlying chemistry.
We are also able to put to rest the "Lemon Test" which we found was a test of little value.