Colored Porcelain Test Info
I spent quite a bit of time researching the stains and looking around the internet for info and pictures. There are some pictures but not very much info. I decided to make these line blend tests and post the results, so that other people may save some time and money when starting out on their colored porcelain adventures.
These tests represent a shotgun approach for testing as many stain line blends as possible, using as little stain as possible. The testing was very efficient and the results are quite accurate. I am quite happy with these charts and I hope you find them useful. However I still recommend doing your own tests. These charts should help you decide what to test and will give an idea of what will happen when one color is blended with another.
A couple things that aren't quite right about these tests.
1) The freaking glaze I used got a little cloudy where it's thick on some of these test buttons. So test your glaze before you put it on 361 colored porcelain tests. But the colors still shine through just fine. While some of them may be a bit cloudy, you can still get a good idea of what will happen when the two colors are blended together.
2) Computer screen colors are always different and I'm not the best photographer in the world. I adjusted the pictures to be as true to the real colors as possible on my screen, but they may look different to you depending on your screen settings.
A little explanation of the charts.
1) The colorant % in the charts is based on moist clay weight. I weighed out 100 grams of casting slip then poured it on plaster and let it dry to moist clay consistency. The 100 grams of casting slip turned to 90 grams moist clay. I calculated the colorant % to the 90 gram weight, but added the colorant to 100 grams of casting slip. I did this because mixing slip together is faster than mixing moist clay. If you want to add colorants to casting slip and get similar results to these charts. 90 grams x 3%= 2.7 grams. Since I used 100g casting slip, 2.7% of 100 will result in the same color saturation. So.....
Moist clay 2% = Casting slip 1.8%
Moist clay 3% = Casting slip 2.7%
Moist clay 5% = Casting slip 4.5%
Moist clay 8% = Casting slip 7.2%
These are just guidelines. Ofcourse different clays and slips won't weigh out exactly the same. After doing all these tests I have realized that when it comes to colored clay, being off by 1-2% won't really affect the outcome very much.
2) These were all fired in an electric kiln to cone 6. The white dot is the raw unglazed English Grolleg porcelain, this clay is fairly close to true white.
3) The test button at the top is the color that was line blended with all the other main colors at the bottom. The line blends are set up vertically. There is no blending of colors from side to side, like in a triaxial blend. These are just line blends of the main top color (next to the white English Grolleg button) with each main bottom color.
3) The mix ratios to the left represent the amount of the main top color (left side of /) blended with the amount of main bottom color (right side of /). So for example on the Dark Red 6021 chart. The 60/40 = 60% Dark Red (at 8%) blended with 40% Mazerine (at 3%), which results in a purple color. If you would like to get the purple color without mixing up the Dark Red and Mazerine separately, then blending them together. You can calculate 60% of the Dark Red at 8% = 4.8% and 40% of Mazerine at 3% = 1.2%. So you could mix 4.8% Dark Red Stain and 1.2% Mazerine stain into a moist porcelain clay body and the results should be something very similar to the purple seen in the chart.
This is an on going project at the moment. I will be updating this page as time goes by.