RichN reacted to perkolator in Adding A Frit To An Oxide To Create An Oxide Wash
You can use either Frit, Gerstley Borate, or make an underglaze with equal parts clay color and flux. Frits, being fired material usually leave a gritty/sandy texture to the wash, some people use CMC, laundry starch, karo syrup, etc to help. Usually I use GB and CMC gum solution, sometimes add a little bit of EPK in it too.
Look up Linda Arbuckle's majolica notes, she's got a lot of suggestions for combos of washes. Most are by volume, not weight.
Here ya go:
RichN reacted to Callie Beller Diesel in VIVID BLUE UNDERGLAZE
The third stripe from the right is 10% mason stain 6305 Teal blue in a white stoneware clay base. This test is at cone 6, but the colour was the same on bisque. The second stripe from the right is 2% cobalt oxide in that same white stoneware clay base, but notice where it’s glazed, there are speckles. If you don’t want the specks, you could try using cobalt carbonate (use a percentage more), or you could grind your oxide. I didn’t.
I don’t think the base matters a whole lot, as long as it’s a pretty white canvas to hold colourants.
RichN reacted to Babs in Tom Coleman's Decorating Colors
I think. Glaze pots add your devorative onglaze colours and washes and fire glazed ware as normal.
Folk s.times spray hairspray or starch to "harden " glaze before applying onglaze as the glaze will possibly adhere to a brush. Glaze will soak up the moisture in the onglaze material really fast so lay colour on as opposed to applying and pressure.
Have to make the onglaze painterly...glycerine, and other products around.
Having said all that some folk fire 3-4 times to get special affects...
RichN reacted to Norm Stuart in Underpainting With Cobalt Carbonate?
We make mason stain color bottles with 2/3 water and 22% gerstley borate, mixed and sieved. To this we add 11.1% mason stain plus 5.6% zircopax for colors other than blacks or greys. The zircopax essentially gives us a white canvas to pain the bright colors on, rather than making red into a pink. Everyone at our studio much prefers this mix to under-glazes as they never blister or change color.
The clay-like properties of gerstley borate also prevent the stain from bleeding into the bisque beyond where you apply it, just as John Baymore mentions adding PVA (white glue) to achieve the same delimiting effect.
Our "color bottle" recipe results in a fairly refractory mix which, once bisque firing after applying the color, doesn't participate with or bleed into ^6 or ^06 clear cover glazes. It can be further diluted with water or brushing medium like propylene glycol or gylcerin. Mixed one part tint bottle with 3 to 7 parts clear or white glaze results in a translucent color.
Making the same media above with cobalt oxide 1.8% in place of 11.1% mason stain, results in a color immediately recognizable as blue rather than the midnight blue-black achieved by mixing the same amount of cobalt oxide with brushing media. Used alone with brushing media the cobalt seems more prone to bleeding.
Cobalt aluminate (CoAl2O4, also sold as a Mason Color 6330) is very refractory when used alone with a brushing medium will eliminate any problems studio members have with cobalt oxide bleeding into a covering glaze - so much so, that use of cobalt aluminate over a large area can result in the over-glaze crawling away from the area covered, which some have used to interesting effect.
RichN reacted to Gabby in Firing Song Dynasty Chinese Funerary Jar / Spokane Washington
As you live in Washington State, I would make an appointment with the head of the Conservation Department at the Seattle Art Museum before you do anything rash. The Seattle Asian Art Museum collection may be the best Asian art collection outside of Japan, and the museum conservator is one of the best in the country.
He has wide and deep experience with objects across the collection, both conserving them and attempting to reverse ill-conceived efforts to conserve ancient things. I have heard him speak several times and been in his conservation lab.
I am sure he can give you good insight into what makes sense to do to take respectful care of this precious and irreplaceable object.