Sunday, 16 August 2009
Search for Shiny Cobalt greens
Triaxial T2 Cobalt Green fired in close formation to Cone 10 oxidation
This blend has been designed for colour; my colourants were Rutile and Cobalt.
Generally the surface quality was semi matte to shiny.The trend was that it became more shiny towards corner C which had Cobalt Oxide at 3% and which probably gave some extra fluxing power and more matt towards Rutile in Corner B at 10% which has an opacifying and matting action in larger amounts.In Corner A the glaze was shiny with a combination of Rutile 6% and Cobalt 1%.The glaze had no crazing but has pinholing and pitting throughout the whole test but Tile 5 is not so bad which could be some external factor like position in kiln and the firing or the actual combination of Fluxing power of Cobalt and stiffening action of Titanium.Also this glaze has high levels of Calcium Oxide provided by whiting which could cause bubbling from Co2 so finding a different source might be useful.
The overall pattern of colour was to move from a Pinky Grey at corner B to Dark blue at Corner C and to Green Blue at Corner A. There were some lovely greens around tiles1.58,13 and 18.Which were very similar colour combination. All had a range of Cobalt 1.00 % to 1.40% and Rutile of 5.20% to 6.00%.
It seems that the right combination of rutile and cobalt consistently give Shiny Greens of varying shades when the flux oxides and Alumina and Silica are constant in the right base glaze..
These Glaze tests have been worked out on Matrix..
Matrix software has been designed by Lawrence Ewing my tutor at Dunedin School of Art