Using Colored Clays

In my last blog post I said I would give you all some pointers on making and using colored clays in this post so here we go. Above can be seen two bead sets made from colored clays. In the petal set the clays were stacked in thin sheets to form a block which was then cut across the colors to give small slabs striped in colored clays. Petals were pinched from these slabs. The color, therefore, goes all the way through the petal. In the coral and shells pendant the colored clays were inlaid on a white background. I will show picture sequences of these techniques on my facebook page once I get the pictures made.
I don't know how many of you out there can actually mix your own clays and glazes from powder and how many need to know how to add colorant to moist clays so I'll give some techniques for both. Actual recipes will be shown at the bottom of this post.
I usually use a high fire (cone 9-11) porcelain body for all of my bead work. I use Mason Stains that are rated as body stains to color the clay because a formulated stain, though more expensive than a raw oxide, is more stable and reliable. Mason Stains are all numbered and named so that is how they are shown in the recipes. Should you want to order some stains refer to them also by number in your order.
The way that the colored clays I am using right now were made was I took soft, moist clay and weighed out 3 to 5 pound batches. I wedged each batch into a ball, made a cavity in the middle of the ball of clay, poured the powdered mason stain into the cavity, added enough water to make a paste of the powder, closed up the cavity and proceeded to wedge the colorant into the clay. I have found this to be a quick and easy method of producing small batches of a lot of colors quickly.
If you want to mix large batches (say 100 pounds or more) of colored clays from powder, mix your base clay first from powder and then add your colorant still in the powdered state. Then mix your clay body in your mixer as you usually would. I don't recommend smaller quantities because most clay mixers can't handle smaller quantities and if you mix the powdered clay method by hand it actually is more difficult and time consuming than the moist clay method of mixing small batches. I am not all that familiar with pugger/mixers. There might be some capable of handling the smaller batches just fine. However, if they are anything like the pugger I've used you will have to clean out the barrel between batches to keep from contaminating each clay color with the preceding color. (Please remember when using and working with powdered clay and glaze ingredients to use a respirator with a silica filter on it.) The 'moist' clay recipes are as follows:
For Pink add 1/4# MS6020 to 5 1/4# of moist porcelain.
For Vanadium Yellow add 1/4# MS6485 to 5# of moist porcelain.
For Teal add 1/4# MS6305 to 3# moist porcelain.
For Black add 1/4# MS6600 to 5# moist porcelain.

Since I originally mixed the colorants into the base clay in the moist state, I'm going to have to translate the 'moist' recipes into 'dry' ones. I thought that you all might like to see how I do this in order to check my math if nothing else. Moist, plastic clay is usually about 80% solids and 20% water. Therefore, 5 pounds of wet clay should have about 4 pounds of dry ingredients and 1 pound of water. (In order to find out what weight of water to add to a dry recipe add 25% of the dry weight of your powders in water. In other words 25% of 4 lbs equals 1 pound. And 4 pounds of powder plus 1 pound of water should give you 5 pounds of moist clay.) With the above in mind to find out how much colorant to add to powdered clay I used the following equation: .25/4.00 = N/100 Solve for N and it gives you 6.25 which can function as a percentage in a normal percentage style clay (or glaze) recipe. Here is my porcelain recipe. For each color wanted add only the percentage of dry powder for that color:
White/Grey Porcelain cone 9-11; Shrinkage 14.3%; Plasticity 7.8
Potash (Custer) Feldspar .................... 26
Kaolin ................................................ 41
Silica ................................................. 21
OM4 Ball Clay .................................. 10

Bentonite ........................................... 2
TOTAL ............................................ 100%
ADD ......
Pink MS6020 ..................................... 5.95%
Vanadium Yellow MS6485 ................. 6.25%
Teal MS6305......................................10.42%
Black MS6600 ................................... 6.25%
I keep my colored clays in plastic containers with their color sample beads wired to the lids. They keep moist for a good while and can be lightly sprayed with water every so often to help keep them so.
If you have any questions please contact me by means of Etsy or my web site contact sheet. Contact URLs follow:
http://www.porcelainjazz.com/contact-form.html
http://www.etsy.com/shop/PorcelainJazz?ref=si_shop