Franny

Thank you, Min and Rae Since posting I've run more tests with three of my 'studio' glazes, and have been really pleasantly surprised! Previously, my testing had been on test tiles - I make small cones that I cut into three so each portion has a base it can stand on in the kiln. This give me the option to use both front and back of the test tile to get as much info as possible! I used most of the oxides in my stores, mixed as described with china clay and matcha, applying these to raw, leather hard clay on the front of each test - a single line, and some brushwork; then on bisque on the back, again a single line plus brushwork; and applied the same relatively fluid glaze to all these tests. The results were quite mixed and most of the oxide decoration looked as if it was blurring. However, I've now tested again on the exteriors of three bowls, using cobalt, copper, RIO, and rutile on bisque, aiming for light and delicate brushwork. I thought that at least two of the glazes used would be excessively fluid, but the results are more encouraging than expected - always nice when this happens! Not yet achieving the 'shrouded' look I'm aiming for, but now looking forward to exploring glaze formulations to achieve this. When I mentioned using matcha tea as a medium for mixing oxides I couldn't remember where I'd seen that reference - or rather it was in an Instagram post that I now can't track down. But I came across this on Richard St John Heeley's website http://www.richardheeley.com/index.html/blue_%26_white.html : ‘Gosu’ is the Japanese name for natural cobalt. The ground cobalt powder was traditionally applied with a thick green tea solution that had been boiled down to a syrup. This mixture would be combined with the ‘Gosu’, enabling it to be applied freely and smoothly during painting. It was allowed to dry and then glazed. The tannin in the tea kept the decoration from spreading when the glaze was applied. Interesting! Don't you just love chemistry?!! I sense a google rabbit hole search of 'tannin' may be on the cards!!! Happy days

Hello I've recently started experimenting with using oxides for under glaze or over glaze decoration. I've searched the site and found many helpful tips, but none have answered my specific queries (below). I'm aiming for subtle line effects and am testing with different glazes. Currently I'm simply mixing tiny quantities of oxides, similarly tiny quantities of china clay, and water (also testing with using matcha tea instead of water, as I read somewhere that this can make application smoother!!) - but I'm not adding any kind of frit. I'm testing on greenware, and on bisque - under, or over glaze (sometimes referred to as in-glaze, on-glaze, or majolica) From the test results I've had so far I'm drawn to the effects of under glaze oxide application, using glazes that are semi-transparent, or translucent, rather than fully transparent, and will continue to experiment, including with layering glazes over the oxide decoration to achieve the 'shrouded' effects I'm looking for. Intuitively, and from my test results to date, using oxides under glaze is getting me closer to this 'shrouded' effect, than using them over or in-glaze - but I'd be really happy to hear your opinions and suggestions about each approach. So, I will continue testing but meanwhile I'd really appreciate some wisdom on a couple of issues: The first is how to control the movement/blurring of the oxide decoration. I've come across suggestions of adding gum arabic or glycerine to the oxide mix to 'fix' the decoration in place, but suspect this will simply burn out in the glaze firing and the oxide decoration will still move as the glaze melts. I suspect that controlling movement and blurring of the oxide decoration may be more a matter of finding the sweet spot of glaze melt-fluidity, and this may involve increasing the alumina to silica ratio in the glazes used over the oxide decoration. Am I on the right track? I would really appreciate your thoughts and tips. The second issue concerns how to ensure that the oxide decoration is fully 'encapsulated' in the glaze to ensure, particularly with toxic oxides such as cobalt, that any potential leaching is minimised. Many thanks, and really looking forward to your thoughts and suggestions!