 Since it's been awhile since we did an intro, we thought it would be a good time to introduce ourselves again!
We met as students at Alfred University where we were both studying ceramic art. After school Rose went to work as a glaze designer in the tile industry and Matt studied ceramic engineering from an artist’s perspective at Alfred and took up teaching glaze chemistry at the school. We started CMW 5.5 years ago to help bring the classes that we developed for teaching at the university to the wider world. Our main goal was to slay all the myths and rumors that permeate ceramics and use ceramic science to help the community make their work the best it can be. We believe that learning how the chemistry of glazes works will ultimately have a profound effect on your studio and we want to show you how to do it. Over the last 5+ years, we've taught over 5,500 classes to over 3,500 students! There is SO much we want to share with you, so we hope that you decide to start your glaze journey with us soon! "See" you all soon! -Matt & Rose  More Tin talk...one more example of what Tin does.
These are the same glaze, again made without Tin on the right, adding Tin to the same batch on the left. This time, the glaze is just increasing the level of opacity. As we said in earlier post today, when we opacify a glaze, aside from making it white, it tends to make glazes “pastel” which is color theory terms, meant to mix a glaze with white. Which lightens the overall appearance. One thing to mention...We are hearing through the grape vine, that Tin prices are about to skyrocket. So if you use a lot of Tin on your work, it may be time to invest. Start your glaze chemistry learning today! Visit www.ceramicmaterialsworkshop.com today! Continuing on the conversation about Tin! Copper Red glazes are interesting as they often contain a lot more Tin than Copper. We’ve seen formula that will have 0.5% Copper and 6x or more Tin. These two glazes are from the same batch. The tile on the right is without Tin. We then added the Tin, and applied a second tile, which is on the left. Both were then fired in the same reduction firing. Why? Well, the copper makes the red, Copper is reduced down to colloidal copper (ultra small) this looks when suspended in a glass. That much is clear. One theory on why the tin is included is that it opacifies the glaze, which makes the red more intense. That doesn’t quite work conceptually, as opacifiers tend to change the colors they are mixed with, into pastel colors. One theory pro-ported by Tschane, in his book copper red glazes, is that it is the reduced behavior of tin that enables the red. Most materials, when reduced, want to reoxidize while still in the firing. The idea is that Tin will reoxidize before cooper, and in that process strips all of the remaining oxygen from the copper, giving it an even more bold color. This behavior is also why the “oxidation flash” in copper red firings is valuable. Our student Mel @a_fizzy_dilu has found some studies that validate this concept. Start learning about your glazes today! Visit www.ceramicmaterialsworkshop.com for more information on our courses.   Reduction is a new concept for a lot of people, that’s because the majority of people are firing in electric kilns, which basically only fire in Oxidation (there are some ways to do it, but they aren’t the safest or most stable).
Most people think about Reduction in reference to copper reds, which we have been talking about recently. But there are a few materials which also can be changed by reduction, and one of those is simple, unassuming Tin Oxide (SnO2). Tin is considered an opacifier, which we use to make glazes white. It used to be used a lot more, but now it is very expensive and Zirconium Silicate opacifies for a cheaper cost. But Tin still has a place in glazes like Copper Reds and Chrome Tin pinks, that we were discussing a few weeks ago. But Tin is important to understand, because in reduction it changes from SnO2 to SnO, which changes the way it interacts with the glaze. Here we have one glaze (4-3-2-1, which you can find on our Glazy page, linked in our profile), all four tests are from the same batch. We mixed it and dipped two tiles, then added 5% Tin and dipped two more. We then fired one of each in a oxidation firing and one of each in reduction. You can see that only one of the glaze (upper right) is white (opacified) the others are all clear. That is because those glazes either didn’t have Tin at all (bottom row) or the Tin was reduced(upper left), changing its properties and removing its opacifying abilities. Visit www.ceramicmaterialsworkshop.com to start learning about your glazes today! There is so much to learn... |
Matthew and Rose Katz - Founders of Ceramic Materials WorkshopThis is a place online to understand and explore how and why our Clay and Glazes work (and don't work). Archives
July 2022
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