Create your
own hues
Mason Stains are among the most versatile colouring materials in a potter’s repertoire. They can be used to add a desired hue to your clay, slip, glaze or underglaze. Composed of fritted (pre-melted) metal oxides and silicates, these pigments offer a level of stability and predictability that raw oxides often lack.
Due to their broad firing range—spanning from Cone 06 (1000°C) to Cone 10 (1280°C)—they are suitable for low-fire, mid-range, and high-fire applications. However, certain color families require specific chemical, thermal, and safety precautions.
Colouring
Clay & slip
Integrating stains directly into the clay allows for deep, structural color, providing the foundation for techniques such as nerikomi and marbling.
Tone
% of stain
(by weight of dry material)
Clay body
Pastel
1% – 3%
White Porcelain
Medium
4% – 7%
White Stoneware
Saturated
8% – 10%+
Any light body (darker stains need less)
White porcelain yields the most vibrant results. Buff or stoneware bodies containing iron will mute the pigment and shift the final hue toward earth tones.
Note: Exceeding 10% can compromise clay plasticity or cause the body to "over-flux," potentially sticking to kiln shelves.
How to calculate the dry weight of clay
If you are starting with a bag of moist clay, you must account for the water content (usually around 20–25%).
{Dry Weight} = {Wet Weight} x 0.75
Multiply your wet clay weight by 0.75 to estimate the dry weight. To avoid "speckling" or uneven streaks do not add dry powder directly to plastic clay. Instead, create a concentrated slurry by mixing the weighed stain with a small amount of water. Wedge this slurry into the clay or high-speed mix it into your casting slip for a homogenous finish.
If you know the specific gravity of your slip, you can calculate the dry weight more precisely. Check your manufacturer’s data sheet for the exact dry-solids-to-liquid ratio.
Modyfing
Glazes & underglazes
Adding stains to a base transparent or opaque white glaze is the most reliable way to build a custom color palette.
While Mason Stains are generally stable, certain pigments are highly sensitive to the chemical composition of the glaze and the peak temperature of the kiln.
Stains perform best in stable, balanced glazes. A glossy transparent base will produce a deep, jewel-like tone, while a matte base will result in a softer, more "stony" appearance.
Chemical and Thermal Sensitivities
Chrome-Tin Pinks & Maroons
Chrome-Based Greens
Encapsulated Stains
(Reds, Oranges, Yellows)
If the base glaze contains zinc, chrome-tin based pinks and maroons will often fade or shift to a dull, muddy gray. Always use a zinc-free base for pinks.
Pink pigments are also heat-sensitive. Firing these to Cone 10 (1280°C) can cause the color to "burn out" or mute significantly.
Many greens will "brown out" in the presence of zinc. To maintain a vibrant forest green, ensure your glaze chemistry is zinc-free.
Avoid over-milling or heavy grinding yellow, orange and red stains. Breaking the zircon "shell" of these pigments will cause the color to vanish or turn black.
For maximum glaze or underglaze vibrancy, fire at Cone 5/6 (1200-1240°C) and avoid long "soaks" at peak temperature.
Test,
Test, test!
Keep a testing log: Record all ratios of stains, clay bodies, and glazes you use. Label each test tile with the exact stain and percentage.
Weight everything carefully: Accurate measurements will allow you to reproduce successful results later.
Start with smaller percentages: Gradually increase the amount of stain if the color is too subtle.
Use kiln shelf protection: If the clay body contains too much stain, it may stick to kiln shelves. Shelf wash won’t save the piece, but it will protect your shelves.
Use separate containers and tools: Dedicated cups and mixing tools make it easier to test multiple colors at once.
Test firing temperatures: As some stains can fade or shift toward gray at higher temperatures, so always test within your intended firing range.
SAFETY
First
Because Mason Stains are concentrated metal oxides (including cobalt, chrome, nickel, and manganese), they must be handled with professional-grade caution.
Skin Irritation and Allergies: Direct contact with dry stain powder can cause skin irritation or contact dermatitis in sensitive individuals. Prolonged exposure can lead to the development of metal allergies (particularly with chrome and nickel-based stains).
Protective Gloves: Always wear nitrile or latex gloves when handling dry powders or concentrated slurries to prevent dermal absorption and skin sensitization.
Studio Hygiene: Use wet-cleaning methods (sponges and mops) rather than sweeping to ensure that heavy metal dust does not become airborne.
Article prepared in collaboration with Petra Mahdalová. Follow Petra on Instagram for more tips on ceramic stains @handandsoul.
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