One of the most common questions I get from people who are new to working with colored clay is not which stain to use, but how much of it to actually add. The percentage guides are helpful, but at some point you need to translate that percentage into a real number on your scale.
That is what this calculator is for. Enter your clay weight, choose your desired color intensity, and it tells you exactly how many grams or pounds of stain to add.
The Short Answer
Mason Stain additions are measured as a percentage of dry clay weight. The three most useful reference points are:
18% for saturated color. This gives you the deepest, most intense result the stain can produce. Worth doing a test tile first, since some colors do not deepen significantly past 10% and the extra stain adds cost without much benefit. 10% for medium tone. The most common starting point for most color families. Browns, greens, blues, and purples usually read well at this range.
5% for pale or pastel results. This is a light suggestion of color rather than a true pigment. Works well for subtle, earthy tones. For pinks and yellows, 5% will often disappear entirely after firing.
How to Use the Calculator
Enter your clay weight in grams or pounds, select the intensity level, and the calculator gives you the stain weight to add. It also shows the total combined weight, which is useful when you are mixing larger batches and need to track your materials.
A Few Things to Keep in Mind
This is based on dry weight. Most studio potters work with wet clay and use the total wet weight as an approximation. It is not exact, but it is close enough for studio use. For precise results, weigh your dry clay before adding water. For the record, I work with wet clay and get consistent results.
Wet color is not fired color. The clay body will look much darker and more saturated when wet than it will after firing. A batch that looks deep and rich on the wedging table can come out of the kiln looking significantly lighter. Always fire a test tile before mixing a full batch.
Not all stains behave the same at the same percentage. A dark blue like Mazerine at 3% will be as saturated as a pink at 16%. The percentage is a starting point, not a guarantee. If you want to understand how each stain behaves by color family, the Mason Stains Color Guide has a full breakdown with recommended ranges for each series.
For FromFran Booklet Buyers
If you are working through any of the booklets and mixing colored clay for the first time, a batch of 500 to 1000 grams of dry clay is a good starting point for a test. That gives you enough to make a couple of slab pieces and a test tile without committing to a full production batch.
For the Bulbo and Garza forms, I typically mix 800 to 1000 grams per color run. At 10% intensity that is 80 to 100 grams of stain, which is easy to measure and repeat.
Related Resource
For color family percentages, specific stain notes, and a full searchable catalogue of Mason Stains, visit the Mason Stains Color Guide.
