Wonder Glaze
A wide firing glaze with great 'fit'

The so-called Wonder glaze is a wide firing glaze ranging from cone 4 to cone 11. It is a buttery smooth white at cone 4, becoming increasingly glossier and translucent at higher cones, particularly in reduction. It displays very good covering strength and very good glaze fit characteristics, even if used as a once-firing glaze.

It can break to a tan color on darker, iron-bearing clays. It takes on brushwork well, qualifying it as a type of higher fired majolica glaze (due to the tin content). Coloring oxides may also be added after minimizing or leaving out the tin oxide. Those wanting to experiment may also try substituting the magnesium carbonate with other fluxes such as barium carbonate or calcite. The tin content in the original recipe can safely be halved when used over white clays (tin is the most expensive component of this glaze) or the covering power need not be so strong.

This is a great glaze for people wanting a glaze that will fire over a wide range and still work. This can be useful in an uneven kiln, e.g. in gas kilns or wood firing kilns, where there can be large temperature differences. It is also a great glaze for functional ware, as there are no toxic components in the recipe.

The original recipe for this glaze calls for an Australian frit, KMP 4108. This low alumina/high silica frit can be substituted with Ferro Frit 3134, Hommel Frit 14 or Pemco Frit P-54. The original frit composition is given further below.

Wonder Glaze Cone 4-11

Frit (see above): 50
Potash Feldspar: 20
Ball Clay: 20
Magnesium Carb Light: 10
Tin Oxide: 10

Frit KPM 4108:

Na2O: .319
Al2O3: .07
SiO2: 1.992
CaO: .681
B2O3: .636

Ababi Sharon has adjusted the recipe with Matrix Glaze Calculator for US ingredients. His modified recipe:

Ferro 3134 41.00
Potash Feldspar (Norfloat) 20.00
Ball Clay AK 24.00
Magnesium Carb Light 10.00
Silica 5.00
Tin Oxide 10.00

The Wonder Glaze was from Janet DeBoos' first glaze recipe book (Glazes for Australian Potters) published in 1978, and was one of the few that were repeated in the second glaze book (More Glazes for Australian Potters) because of its wide application and usefulness. It was developed in glaze schools that she used to run in the early seventies doing simple flux substitutions in standard "glaze shapes". (50/20/20/10 being one such "shape") It has been widely used throughout the Adult Education Ceramics sector (and beyond) since.

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