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Manganese is the new Cobalt. Haha. Ok, maybe I can't back that up at all… but there have been some killer iridescent glazes (@lisazolandz) showing up in my feed lately! @ceramicmaterialsworkshop just posted a sweet tile with a manganese crystalline glaze today. They've got me thinking back to the scanning electron images I took back in grad school at Utah State. Here's one from my vault. It's a 5000x zoom in of a manganese crystal nucleus. Pretty wild, eh? If memory serves, this glaze was a variation of David Shaner's glaze, which was given to my by John Tilton. 68% Custer, 2% EPK, 27.5 Manganese Dioxide, 2.5% Granular Manganese. . . _________ #manganese #glazetests #research #art #ceramics #glaze #SEM #porcelain #microscope #clay #mn #kiln #crystal #firedinaskutt #testing #ceramicglaze #artistsofinstagram #science #element #ceramicart #crystalline #glazerecipe
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Here’s a great video that’s absolutely worth the watch!
Without a doubt, Pioneer Pottery is the best resource for you diggers out there. Micheal Cardew was an absolutely incredible potter and glaze wizard. Here’s the book summary from Amazon:
Pioneer Pottery is one of the classic texts in ceramic literature. Its author, Michael Cardew, was one of the seminal figures in British ceramics and this book, written partly in response to his time spent in Africa, has influenced generations of potters around the world.
As one of the early and influential figures in British ceramics, Michael Cardew was asked in 1942 by the Crown Agents to go to Nigeria to set up a pottery training center. It was his experiences there, as well as his previous time spent in the Gold Coast, that formed the basis for this book. In addition to discussions about the basics of clay and glaze materials and their properties, Cardew shows how to make pots in the Kwali, Jebba, Vume, Ilorin, and Hausa traditions of western Africa. This book is the first book to discuss all aspects of the pottery making process from materials through marketing. Michael Cardew found it necessary to find out and do everything for himself, and this is what lies behind this book. The consequence is that it is filled with a sense of discovery and firsthand knowledge.
A second amazing book is Glazes From Natural Sources. I like Sutherland’s perspective, and his instructions on building a home made ball mill and pugmill are super interesting. Although US buyers will probably find this one a little more expensive, it’s a great resource to have. Here’s the Amazon summary:
Any real education in ceramics must involve, from the outset, an appreciation of the source materials—the rocks around us. While good, throwable clay may be a regional commodity, there is no part of the world that will not yield potential glaze materials in abundance. Potters therefore need to know how to exploit the special properties of local rocks quickly, reliably, and methodically. This new revised and updated version of Brian Sutherland’s classic book on making glazes from natural sources explains how to locate glaze material and construct, test, and use the glazes created.
Glazes from Natural Sources discusses rock types and other likely sources of supply, the making of test pieces, and the use of blend systems and constructions. The author also clarifies the Seger system of glaze presentation for those who, like himself, have found it difficult to grasp and apply. He covers, and supplies, formulae for glazes for all temperatures—from raku to stoneware and porcelain—and includes sample recipes. The book emphasizes careful planning and control to ensure results that are repeatable. This makes the science behind making glazes from natural sources both understandable and feasible.
Glazes from Natural Sources is fully illustrated, with diagrams of techniques demonstrated as well as images of the finished works of potters to show the results of these natural glazes. First published in 1987, this book is considered a classic by ceramicists. This edition includes a new chapter by glaze expert Nigel Wood.
Here’s a Podcast I did at NCECA! Check it out if you’ve got some time.
Not exactly Oil Spots in the truest sense, these two variations were concocted and tested along with the rest of my oilspots glazes. Both of these recipes utilize some local dolomitic limestone I found and incorporated into the recipes. If you want to re-create these, using a mix of 1/2 and 1/2 Dolomite and Limestone will get you very close.
Here’s one that’s a bit of a kitchen sink: Lots of iron, manganese, cobalt, and copper.
Here’s my Lava Oil spot firing schedule, which always looked best fired in a neutral/oxidation atmosphere in a gas kiln.
You might notice that this one has a significant addition of Cobalt, half and half Custer (Potash) and F4 (Soda) Feldspars, calcined talc, and 2% Manganese. Typical that I changed too many things to give a really useful side-by-side comparison. But I suppose when I’m coming up with new variations, that’s always been my style.
Some observations on this one:
Cobalt goes a long way and pretty dramatically alters an oilspot. With a .25%-.5% addition you get a nice shift from brown and russet glaze matrix to a darker solid black glass. Beyond 1% you can get some really nice silvery qualities to the spots. The drawback is that the more you add, the more refractory the glaze tends to get – and the longer it takes for the glazes to heal.
“I have not failed. I’ve just found 10,000 ways that won’t work.” – Thomas A. Edison
Just spent a bit of time inputting this old recipe into Glazy.org. Pretty Sweet!