HOW TO COLOR CLAY WITH MASON STAINS

Why color your own clay?

FREEDOM & OPTIONS

You can purchase pre-colored clay but if you want more control over color and hues I recommend mixing your own. You can use any clay body, wet or dry, but white clays firing at or above Cone 5/6 provide vibrant color results. I prefer to mix the stains into wet clay bodies. The Mason Stain Company has a very informative web site with colors recommended for clay bodies. Take a minute to read this area as there are some stains that just will not work with clay bodies due to chemical composition.

http://www.masoncolor.com/ceramic_stains.asp

US Pigments is also a stain supplier. No matter which stains you choose, you should buy small samples and test them first with your clay body.

Choosing the Right Mason Stains

The Mason website has listings of all the colors available with a guide showing which ones are suitable for using in clay bodies, how high they can be fired and which ingredients to avoid in your clay and glazes. 

Why does this matter? Every clay body has ingredients that can react to a colorant. If your clear glaze has the wrong ingredient in it, it will change the colors or bleed them. Some clays simply cannot make the stain work.

You can be reasonably safe if you stick with their guidelines, but safe is not always fun. I have tried dozens of other stains with great results. The trick is to check the guidelines, then test every single batch you blend in order to see what happens to the color with and without a glaze. Then you can decide whether to keep using it or not.

I had a pink stain and a bright yellow stain ... both fired to the most lovely pale green. I would not keep these since it is so easy to forget that the color of the wet clay isn’t what you get when fired. 

How much Stain to use?

This is a very common question. I use a high concentration of stain because it is much easier to store 3 lbs of concentrate vs. 12 lbs. of pastel shades.  Properly stored the clay will last for years and it is very easy to knead in some white clay to get the color you want.

The dark colors require less stain than light colors. For blacks, dark blues and greens I use about 5-8% stain. For yellows, pinks, mauves I use between 12-20% stain.

I like vibrant colors and use a lot more Mason Stain by % than most do.

My basic Mason Stains with percentages.

#6020 Pink @ 12 – 20 %

#6450 Yellow @ 12 – 20 %

#6300 Blue @ 5 – 8 %

#6242 Bermuda Green @ 12 – 18 %

#6600 Black @ 5 – 8%

How do you measure the stain? 

Say you want 10% stain, then that would be 10 grams of stain to 100 grams of wet or dry clay. I really don’t think it is crucial to use one or the other type of clay. As long as you make tests of your colors and keep records, you will be able to repeat the results no matter how you mix it. You can use the same % to make slips.

How do you mix the stain into the clay?

Even though it is a messy job, it is also a very simple job.

CAUTION: Do no breathe the dust from Mason Stains or dry sand the finished colored clay without a proper breathing mask.

In order to avoid the dust problem, mix the Mason stains in a sealed plastic bag with just enough water to create a creamy solution. Then create a well in your clay and pour in the mixture. Knead the clay until you like the color result.

IMG 5977

I use a large commercial machine to mix the stain/clay solution until the color is even throughout the clay body. You want the finished clay to be soft as cookie dough. My mixer is a Hobart A120T and is 1/2 hp. I bought it used.

Some potters buy an old Hobart mixer and use it in the studio to mix a very thick slip. I don’t think the motors on the kitchen models could handle stiffer clay. They let this mixture dry until it is the consistency they want.

Usually you mix the clay until the color is even, but you can also stop mid way to get a nice speckled effect with the color.

I keep my clay wrapped in a damp cloth and double bagged in plastic. You could also totally dry it, store and re-hydrate when needed. Here are some images supplied by Yvonne Cooper, one of my students who uses this process. 

**Just remember that once you use a kitchen mixer in the studio, it should never go back in the kitchen. 

YC-mixerYC-plaster


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I always make sample discs of each color for reference. You cannot count on each batch turning out exactly the same.

 I also make sample discs of the colors combined with white clay and with each other in a range of percentages.


You can expect the color to darken as you fire at higher temperatures. 

If you like the color when it is wet, then it is too dark and you should add at least 50% more white clay and check again. 

Sometimes you can barely see the color but it is there. Always mark your storage bags so you don’t confuse it with white clay

YC-Storage


I hear comments about how expensive stains are but consider that colors last a long time, especially if you are mixing in plain white clay. I keep colors stored in plastic bags for years with no ill effects.

Yvonne stores hers in plastic food storage containers with a fired sample on top for easy identification.



Another area of concern is SAFETY You do have to be careful not to inhale the dry powder while mixing, so use a proper breathing mask while measuring the stain. After the stain is wet and creamy, they are safe to work with and fire. Some people choose to wear latex gloves. Another area for concern is dry sanding. Always wear a breathing mask to avoid both the dry stain and the silica in the clay.

I have experienced fluxing with some stain colors when they are used in a very concentrated form so you do have to prevent them from sticking to the kiln shelf. I sprinkle some alumina hydrate under them when firing these.

IF YOU WANT TO COLOR YOUR CLAY WITH OXIDES I RECOMMEND ROBIN HOPPER’S BOOK “MAKING MARKS”. HE HAS A TERRIFIC SECTION ON THIS.


For more options and information on coloring clay, look at the WORKSHOP page of my site to find a class near you. If there isn't one, consider recommending my workshops to an Arts Center in your area.

Copyright © Chris Campbell Pottery, LLC  chris@ccpottery.com