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eutectics - their pratical use

updated wed 15 jul 98


David Hewitt on tue 14 jul 98

I have found that some understanding of eutectics most useful and I
would be interested in knowing of other potters experience with their
practical use, in particular with the use of triaxial phase equilibrium
diagrams as a means of helping with glaze formulation.
For many years now Mike Bailey and I have used such graphs for plotting
our glaze tests, seeing in which direction we need to adjust recipes,
for what result we want, and as the starting point for compiling glaze
recipes for testing. We analyse recipes and sum the result into Acidic,
Amphoteric and Basic oxides. Each corner of the graph is 100% of each of
these components. If you do this with a range of recipes with similar
Basic oxide components you will soon see where you get transparent shiny
glazes, where you will get alumina matts etc. According to what result
you are seeking, you can then take an area of the triaxial and 'cover'
this area by translating the triaxial point percentages into the bases
for constructing new recipes.
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP6 1DQ, UK. Tel:- +44 (0) 1633 420647
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