For the materials research portion of this semester, I chose to do a line blend of Kona F-4 Feldspar and Georgia Kaolin, two of my favorite dry materials. I love the slightly crispy feeling of scooping Kona F-4, and the fluffiness and color of Georgia Kaolin.
Kona F-4 (Na2O.Al2O3.6SiO2) is a soda feldspar, used as a flux in many glazes. The soda portion of this feldspar is the dominant flux in this material. Kona F-4 is a source of Insoluable Sodium and Potassium
Georgia Kaolin ( Al2O3.2SiO2.2H2O) is the source of Silica in this blend, so that this combination will have a glass former and a flux, hopefully resulting in a surface varying from dry to semi-gloss, anticipating a relatively smooth surface.
Each test cup contains a total of 100 grams of material and 1/2 cup of water. There are nine test cups total, with the following proportions:
90g Kona to 10g Kaolin
80g Kona to 20g Kaolin
70g Kona to 30g Kaolin
60g Kona to 40g Kaolin
50g Kona to 50g Kaolin
40g Kona to 60g Kaolin
30g Kona to 70g Kaolin
20g Kona to 80g Kaolin
10g Kona to 90g Kaolin
While weighing out these materials, the Georgia Kaolin quantities were nearly double that of the same gram amount of Kona F-4. Upon adding water to the tests, the more Kona F-4 heavy tests settled firmly to the bottom of the cup while the Georgia Kaolin heavy tests remained well suspended.
So, I didn’t really lay these out super well, but in any case, the Kona starts 9/1 on top, and Georgia Kaolin is 9/1 on the bottom. The right test tile was fired to Cone 06, the left to Cone 10 in reduction.
At Cone 06, all tests were somewhat fused while a bit powdery, but the Kona heavy tests came completely detached- the 9/1, 8/2, 7/3, and 6/4 dots all were loose upon unloading, crispy, but totally detached from the clay. The Kaolin dots were still well attached, but dusty feeling enough to set my teeth on edge.
At Cone 10, the top two Kona heavy tests were well melted and fused to the clay, but clearly had crawled inward from their initial width- would indicate a tendency to crawl if used over a large surface. The next three tests were fairly melted to each other, but beginning to peel up at the edges. The last four test dots, starting with 4/6, Kaolin heavy, ranged from lightly creamy, but scaling off of the clay, to crusty and popping off the surface, to well fused but downright crusty. Interestingly, there is a gray/purple tint in 3/7 and 2/8.