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Enamels and Overglaze Decoration

This cup is made from Lantz earthenware clay from Nova Scotia, Canada, white slip, clear glaze and overglaze enamels. While I was a student at the Nova Scotia College of Art and Design in Halifax, I experimented with the use and manufacture of enamel glazes. Enamels are glazes that fire at extremely low temperatures (about 1200F) and fuse onto the surface of an already fired glaze. I was interested in the effects of having physical layers of color overlapping each other.    


Cup, 2008. earthenware, white slip, sgraffito, clear glaze and overglaze enamels



In order to have a glaze that fired at such a low temperature, overglaze enamels are typically lead-based. With the help of my professor, Walter Ostrom, I found a collection of formulas for glazes that mature at a range of low-temperatures that do not contain lead. 

Once I found a formula that worked, I experimented with various colorants; mason stains and oxides. I also experimented with mediums for applying to glaze to a non-porous surface, like fired ceramic. 

At the time, I was interested in replicating the surfaces that I found in the work of Henry Varnum Poor and Ogata Kenzan:


Plate, Henry Varnum Poor


Ogata Kenzan, Mukzuke with Camellia Design. Collection of the Brooklyn Museum



What I saw in that work was color that was a material physical layer, a change in surface texture/sheen/, and, most importantly, a design that was executed in stages and multiple firings. That idea of returning to a piece and layering up glazes to complete a piece was revolutionary to me at the time. It opened up so many avenues for my work ever since. 



Folded Vase, 2015


Bottle Vase, 2016





Below are the formulas that worked for me and the source. 

EG-11 (modified)

Ferro Frit #3134 78.5

Lithium Carbonate 19.5

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CMC Gum 0.3%

Bentonite 0.4%

H20 45-50%


Sources:

Click link to open PDF file 

Water and Gum Ratio in Glazes

"Earthenware Glazes"