The percentage question is the one I get asked most often, especially by people working through the FromFran booklets for the first time. The answer is not as simple as "a little goes a long way," because that is only true for some colors. For others, you need far more than you would expect to get any visible result.
This is the guide I wish I had when I started coloring my own clay. Below you will find a breakdown by color family, the most common mistakes, and an interactive tool where you can look up any Mason Stain by name or number.
What Are Mason Stains?
Mason Stains are commercially prepared ceramic colorants made from metal oxides that have been processed to be stable, consistent, and safe. They are manufactured by Mason Color Works and are one of the most widely used colorant systems in studio ceramics worldwide.
Unlike raw oxides, Mason Stains fire predictably across a range of temperatures and clay bodies. That reliability is what makes them so popular in studio work, and especially useful when you are building from templates and want repeatable results across multiple pieces.
They can be used in clay bodies, slips, engobes, and glazes. The percentages, however, are completely different depending on the application. Everything in this post refers to clay body use only.
How the Percentage Works
The percentage refers to the dry weight of stain relative to the dry weight of clay. If you are working with 1000g of dry clay, a 5% addition means 50g of stain.
In practice, most studio potters work with wet clay and weigh the stain by percentage of the total clay weight as a close approximation. It is not perfectly accurate but it works well enough for studio use.
Percentages by Color Family
This is where most guides fall short, because they give you a single number and move on. The reality is that the range varies dramatically between color families, and even within a single series.
Dark colors: 3 to 6%
Black, Mazerine Blue, Navy, dark greens like Peacock. These stains are very concentrated. Three percent is often enough to achieve a deep, saturated result. Adding more will not necessarily intensify the color, and at high percentages it can start to affect the workability of your clay body.
Mid-range colors: 5 to 10%
Browns, teal, cobalt, purple, most greens. Start at the lower end and test before committing to a full batch. These are the most forgiving colors to work with.
Light colors: 10 to 16%
Pink, yellow, lavender, shell pink. This is the range that surprises people the most. These stains are less concentrated, and the color often looks much paler out of the kiln than it did in the wet clay. Going below 10% with most pinks and yellows will give you almost no result at all.
A few colors sit in their own category entirely. Shell Pink, for example, will read as a pale blush no matter how much stain you add. That is just the nature of that particular colorant. Knowing this before you mix saves a lot of frustration.
What Affects the Final Result
Clay body color
White or light-colored stoneware gives you the most accurate read on the stain. Iron-rich or dark clay bodies shift the final color, sometimes dramatically. A yellow stain on red earthenware will look completely different than on white stoneware.
Firing temperature
Most Mason Stains are stable from cone 06 to cone 6. The encapsulated series, which includes oranges and reds, is not stable at cone 10 and will burn out or shift significantly in reduction firing.
Surface finish
Unglazed colored clay fires to a matte, slightly raw surface. A clear or satin glaze over colored clay will saturate the color and give it more depth and richness.
Mixing
Even distribution matters. Wedge the stain into your clay thoroughly, working in stages. Alternatively, mix the stain into a slip first and then incorporate it. Uneven mixing shows up as streaks in the fired piece.
A Note on Wet Color
Mason Stains look very different before and after firing. A clay body that looks pale or grayish wet can fire to a much richer result. The opposite can also happen. Always fire a test tile before mixing a full batch, and let it cool completely before judging the color.
A Note for FromFran Booklet Buyers
If you are working through any of the FromFran slab-building booklets and experimenting with colored clay for the first time, a few things worth knowing:
The vessel forms in the Nº3, Nº4, and Nº5 booklets work especially well with colored clay bodies because the slab construction lets you plan the color before you build. Unlike wheel throwing, you can roll out a test tile from the same slab you are about to use and fire it beforehand.
For the Bulbo and Garza forms specifically, I have had good results with Peacock Green at 4% and Mazerine Blue at 3%. Both hold their color well under a clear satin glaze.
If you do not have a booklet yet and want to start building, you can find the full series below.
Mason Stains are one of the most accessible ways to introduce color into your handbuilding practice. The key is understanding that not all colors behave the same, and that testing is not optional. A single test tile fired before your batch will save you far more time than it costs.
If you found this guide useful, save it for the next time you are mixing. And if you have questions about a specific stain that is not in the tool, feel free to reach out.
Fran
