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September 16, 2009

The Happy Accident: How a Ceramic Artist Turned the Product of a Kiln Firing Mishap into a Gem

by Jennifer Harnetty Read Comments (11)

	As potters, we’re all familiar with the happy accident (we’re also all too familiar with the unhappy accident, but that is a different post). Sometimes happy accidents can lead artists down a brand new path. One such happy accident did just that for ceramic artist Mary Cay. This one involves the little jewel-like drips of glaze that are sometimes found on kiln shelves after dripping off of a heavily glazed pot. Potter Mary Cay became enamored with these little jewels and began collecting them. She knew she wanted to do something with them in her work and decided that she needed to figure out “how to cultivate them, rather than mine them.” Today, she shares the results of her two years of trial and error, including the recipes and instruction you’ll need to try making your own glaze kiln jewels. - Jennifer Harnetty, editor.
Kiln Shelf Preparation The first step in the process is to apply a wax-resist/alumina-hydrate mix to bare mullite kiln shelves. Mix equal parts wax resist and alumina hydrate by volume. Stir well and often. For Limestone Base Glaze, use four parts wax resist to one part alumina hydrate by volume. For Judy Cornell’s Moon Celadon glaze, use two parts wax resist to one part alumina hydrate by volume. After washing the kiln shelf with hot water, quickly apply the wax-resist/alumina-hydrate mix to the shelf with a sponge brush (purchased from any hardware store). Allow drying just to the point at which the wax is no longer tacky and then apply a second coat. For jewels larger than 1/2 inch in diameter or for the Celadon kiln jewels, apply a third coat. Note: If the wax dries too much, it will repel the next layer of kiln wash. To remedy this, apply hairspray that contains alcohol in even, sweeping coats to soften the wax. Applying Kiln Wash Mix the wash to the consistency of heavy whipping cream and apply at least two coats to kiln shelf that has been prepared with the wax-resist/alumina-hydrate mix above. For larger (more than 1/2 inch diameter) kiln jewels, apply additional coats. To make a smooth surface, spray the kiln wash with water from a spray bottle and allow to dry between coats.
Crazy about glazes? Be sure to download your copy of 10 Tried and True Cone 6 Glaze Recipes: Recipe Cards for our Favorite Mid-Range Pottery Glazes, one of the FREE downloadable studio resources from Ceramic Arts Daily.
Glaze Preparation After mixing batches of the glazes, fill several plastic containers and allow them to sit uncovered overnight. The next day, decant all the water that is sitting on top and remix the glazes with a fork. Allow them to sit for another two or three days and decant again. The glazes should then be a very thick paste. Humidity clearly effects the decantation process. In Colorado, a semi-arid state, this process can be completed in three days.   For Judy Cornell’s Moon Celadon, add 1 teaspoon of sodium silicate at a time, and remix to deflocculate the glaze just enough to hold a hemispherical shape as it is extruded from a syringe. For every 24 ounces of decanted glaze, 2 tablespoons of sodium silicate are usually added. For the Limestone Glaze, no sodium silicate is necessary. Glaze Application Apply the glazes to the prepared kiln shelves through a syringe and fire to Cone 10 in reduction. After firing, the kiln jewels will release from the shelves and can be washed off. If necessary, the bottom can be sanded with a drywall screen. Post Firing Kiln jewels can be refired onto ceramics using Cone 017, 05 or 04 glazes as an adhesive, or attached with epoxy in a cold surface treatment.
Recipes Kiln Wash for Limestone Glaze Calcined Kaolin 50% Silica (Flint) 50% Total 100% Kiln Wash for Judy Cornell’s Moon Celadon Alumina Hydrate 60% Calcined Kaolin 20% Kentucky Ball Clay 20% Total 100%
The following recipes were given out during the summer session at New York State College of Ceramics at Alfred in 1998.
Judy Cornell’s Moon Celadon Glaze Recipe Cone 10 Whiting 16.2% Kona F-4 Feldspar 50.5% Silica (Flint) 33.3% Total 100% Add: Bentonite 1.0% Barnard Clay 5.5% This is a glaze that settles easily, so add 3 tablespoons of Magnesium Sulfate (Epsom’s Salts) to a 10,000-gram batch of glaze. Limestone Glaze Recipe Cone 10 Whiting 15% Custer Feldspar 49% Kaolin 13% Silica (Flint) 23% Total 100% Add: Bentonite 2% Stains can be added to this glaze according to the manufacturer’s recommendations. For Yellow Glaze Kiln Jewels, 3% Cerdec yellow stain was added. Carbonates and oxides also have been added to this recipe with success by using various proportions. A strong cobalt glaze was mixed with this glaze to produce the Sky Blue Glaze Kiln Jewel, but cobalt carbonate or oxide also could be used. A wash of copper sulfate can be sprayed or brushed on to create the Copper Sulfate Glaze Kiln Jewels.  To learn more about Mary Cay and see more images of her work, please visit www.mary-cay.com. This post was excerpted from Glazes and Glazing: Finishing Techniques, which is available in the Ceramic Arts Daily Bookstore.

 

Tags: Ceramic Decorating Techniques, Ceramic Glaze Recipes, Cone 10 Glaze Recipes, kiln wash

11 Comments

1. Chris | September 16th, 2009 at 1:31 pm

   I have loved these little treasures for a long time as well. I have carefully harvested these colorful drips and gave them to a friend to mount in her jewelery. Never two pieces alike and she has made some award winning pieces.

2. M | September 16th, 2009 at 2:11 pm

   What is your friend’s name? Does she have a website? The beauty of “farming” kiln jewels is that one can be fairly consistent…or one can order them from my website. I make beautiful earring simply by using E6000 glue and mouinting them in sterling silver bales. I have a pair listed in my etsy shop “Infinityart”

   Thanks for the comment. MC

3. Chris | September 17th, 2009 at 5:54 am

   It looks great ! It must have been a long and difficult “way” to get there !?!

4. Vivienne | September 17th, 2009 at 6:25 am

   I dont wish to spoil a party but the mix of wax, hairspray and copper sulphate sounds very toxic. The jewels are beautiful, but please be careful for your health’s sake.

   V

5. Stacey | September 18th, 2009 at 8:59 pm

   Do you have any tips on how to attach these to ceramic works? Your website is great!

6. Linda | September 19th, 2009 at 4:54 pm

   Is it possible to do these in an electric kiln??

7. Linda | September 19th, 2009 at 4:57 pm

   OOPS forgot my manners. Thank you so much for sharing!!

8. Samuel | September 27th, 2009 at 4:34 am

   I am glad I have finally found a good site to help me in persuing my course and the opportunity to be updated by the monthly magazine in the world of ceramics.
   Thanks so much.
   Samuel.

9. becky | October 1st, 2009 at 3:01 am

   I am coming in as a novice here, with just a little work on a wheel and a few firings. I can’t tell you how excited I am from reading the articles of you wonderful creative people who are developing this craft as a dynamic process every day! My future is opening up before me! Thank you.

10. Alan | October 13th, 2009 at 6:38 pm

    Presumably fixing the kiln jewels using glaze means that they have to be fired on a horizontal surface. They would surely fall/slide off if fired on a vertical surface. Result = unwanted, (probably), flattened, (possibly), glaze drips.

11. Linda | October 16th, 2009 at 7:39 am

    Do we get ans. for the questions????? I still want to know if you can make them in an electric kiln????? Thank you, Linda

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