MarkS Posted April 20, 2011 Report Share Posted April 20, 2011 I apologize in advance if I'm not using the right terminology.... I am wondering if there is a way to make your underglaze colors for bisque firing (cone 06) or for use under glaze for high firing (cone 6). I am looking for a deep cobalt blue to use under clear glaze. I don't know how my great-grandfather did it but they only fired each piece once. Thanks! Link to comment Share on other sites More sharing options...
Lucille Oka Posted April 21, 2011 Report Share Posted April 21, 2011 I apologize in advance if I'm not using the right terminology.... I am wondering if there is a way to make your underglaze colors for bisque firing (cone 06) or for use under glaze for high firing (cone 6). I am looking for a deep cobalt blue to use under clear glaze. I don't know how my great-grandfather did it but they only fired each piece once. Thanks! Try Mason Stains; also look for the underglaze medium. Go to the Mason Stain website or look in a good ceramic supplier catalog such as Ceramic Supply of New York and New Jersey in Lodi, New Jersey, their catalog reads almost like an encyclopedia and it can now be downloaded to your computer. If you are just looking for the cobalt color; the oxide is very strong stuff use it very sparingly and do not use it around women and children. The carbonate is not as strong but the color is still intense, and use caution with this as well. Cobalt is expensive and the price fluctuates. It is best to do some research before using cobalt or any other oxide for that matter. Find out what oxides to use under what conditions. And what can and cannot be used safely. Cobalt is stable at high temperatures. Hence the reason for the early Porcelain wares having mainly cobalt blue color. Many of them were single fired wares. Single fired wares are possible, for us today but be sure your pieces are well made, fire low and slow early on. Also be aware cobalt may 'spit' in the firing and little blue ‘dots’ may be found on the ware from that firing. Or you can try Amaco LUG22 Dark Blue, Amaco Velvet Series V386 Electric Blue and V336 Royal Blue. They come in 2 ounce or 16 ounce jars. Ask for and read the Material Safety Data Sheets. To color check, be sure to test before you apply to your ware. Link to comment Share on other sites More sharing options...
Chris Campbell Posted April 21, 2011 Report Share Posted April 21, 2011 One other caution ... Do tests of your clear glaze with the product you choose to make sure it does not affect the cobalt color or sharpness of your designs. Link to comment Share on other sites More sharing options...
Bobg Posted April 21, 2011 Report Share Posted April 21, 2011 I use a 3% cobalt slip, bisque fire at ^06 and glaze fire at ^6. I have played around with putting cobalt and then glazing the greenware and firing. The color came out alright, but I wasn't satisfied with the end result and now fire the green ware with cobalt and then glaze and fire. I pay $12.00 for a quarter pound of cobalt oxide and $8 for a quarter pound of mason stain. I mix up a quart at a time and it last for quite a while. Bobg Link to comment Share on other sites More sharing options...
MarkS Posted April 26, 2011 Author Report Share Posted April 26, 2011 I suppose slip decorating may be a more proper term for what I'm thinking of. What kind of slip do you mix your cobalt with? 3% by weight I take it. Link to comment Share on other sites More sharing options...
Natas Setiabudhi Posted April 28, 2011 Report Share Posted April 28, 2011 Actually you can use cobalt alone for underglaze color. But practically, it's difficult for application. I usually mix it with other oxides, such as whiting as a flux and flint as a refractory material. For better application, the combine materials are calcined until they sinter into a hard but unmelted mass. The material is then ground in a ball mill to a very fine particle size. Good luck:rolleyes: Link to comment Share on other sites More sharing options...
Natas Setiabudhi Posted April 28, 2011 Report Share Posted April 28, 2011 Actually you can use cobalt alone for underglaze color. But practically, it's difficult for application. I usually mix it with other oxides, such as whiting as a flux and flint as a refractory material. For better application, the combine materials are calcined until they sinter into a hard but unmelted mass. The material is then ground in a ball mill to a very fine particle size. Good luck:rolleyes: Link to comment Share on other sites More sharing options...
Bobg Posted May 5, 2011 Report Share Posted May 5, 2011 I suppose slip decorating may be a more proper term for what I'm thinking of. What kind of slip do you mix your cobalt with? 3% by weight I take it. Mark, I just use the clay that I using to turn and put everything in a blender with a little water and let it turn until it's all mixed up and then adjust the thickness of it. Yes, everything is by weight. I've used dry clay, but it doesn't seem to make a difference if it's wet or dry. Bobg Link to comment Share on other sites More sharing options...
Marcia Selsor Posted May 6, 2011 Report Share Posted May 6, 2011 I use my porcelain slip. I tried a LUD on my shellac resist and the LUD flaked off with the shellac. SO back to making my own slip. Marcia Link to comment Share on other sites More sharing options...
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