Colorforms

Presentation given at the annual conference for the National Council on Education for the Ceramic Arts in 2019 held in Minneapolis, MN.
For more information please visit: www.nceca.net
Presentation by Rose Katz
I will explore the chemical role of all the major colorants: Titanium, Chrome, Manganese, Iron, Cobalt, Nickel, and Copper. How do we consider them when we examine glaze chemistry, and what can we learn from them when we do?

[@BearHillsPottery]

Thank You for doing this research and for sharing your results. It is very informative and I look forward to seeing future updates and submissions. Well done!

[@louiskatzclay]

This is a game changer in many ways. Thank you both and the help too! I wonder,,,, and I really do not know, but I suspect that additions of chrome to low alumina and silica mixes would not get the glazes to move out of the deep corner of the stull map ... But if it did, it might be really spectacular. Another possiblity is combining the Chromium with the research on Boron and running a set of tests perpendicular to the surface (increasing amounts of boron) at higher levels of chrome,,,, I have a hard time picturing this well enough to even come to any theories. It seems like it might confirm or help confirm your idea for chrome.

[@____Ann____]

Super interesting. If you want to skip the intro (glaze basics) go to 20:30.

[@YAYKUTTEL]

Great lecture! That Neodynium is doooopppppeee

[@2ndPortal]

Will we ever get the iron video?

[@missylee5]

This is a great video, but there's one part bothering me. At 26:00 Rose says based on the tests they would categorize Cobalt Carbonate as an alkali earth, for reasons they don't have time to get into. Looking at the test result photos you would think it functions as an alkali metal, since when used this way the glaze turned out clearly more matte/glossy when expected to, as opposed to the photos of it being used as an alkali earth. I really wish they would've at least given a quick explanation as to why they went with the less obvious choice there.

[@garyohlman]

Very cool so when is the Iron discussion?

[@jimwampol6657]

Love your presentation but I'm a little confused. When you get to Nickel Carbonate I don't understand your horizonal plot points for Silica. The top of the page shows 2.0 Silica but plot point is about 3.5. This holds true for all the following elements after this. Can you clarify for me please?

[@atomicgirl67]

At 19:25 the Stull chart shows a red dot in the "bright" zone, and it's clearly not in the craze zone. However the corresponding glaze sample shown is clearly crazed. I was expecting a good glaze fit with non crazing, given the position of the point on the map. Can someone help explain this to me?

[@AnarchistEagle]

The craze line on Stull's chart is just from his observations with his specific ingredients. He used K2O and CaO as his alkaline metal and alkaline earth respectively. Had he used Na2O instead of K2O, he would have gotten a different craze line. Crazing is not a result of a specific ratio of silica to alumina, it's caused by a mismatch in the coefficients of expansion between the glaze and the clay body. It's theoretically possible that a different clay body with the same glaze applied will have no crazing.