Underglaze​

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Commercial pigments/ceramic stains and oxides mixed specifically to be painted on ceramics before a transparent or translucent glaze is applied on top.

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• Applied before glazing: Goes onto bisqueware (already once-fired clay) or greenware (unfired clay), depending on the technique.

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• Stays in place during firing: Unlike some glazes that can run or move, underglazes tend to be more stable.

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• Pigmented: Underglazes are intensely pigmented, meaning they are highly colored with ceramic stains or oxides.

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• Color retention: Colors are designed to remain close in color at most firing temperatures. Clay Space high fires to cone 10 causing some colors to dull, mute or shift slightly. The colors do become more saturated and vibrant in the glaze firing than when first applied or bisqued.

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• Opaque: Underglazes are typically opaque, allowing you to see the colors clearly.

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• Fires Matte Without an Overcoat: Underglazes by themselves aren’t shiny—they need a clear glaze over top to become glossy or food-safe.

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• Coverage: Should not be applied to the bottoms of pieces. While it does not gloss over, each color has different tendencies, each batch can have different qualities, and can pose a risk that it could fuse to the kiln shelf.

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Mayco (Brand) Stroke and Coat “Wonderglaze”

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• Mayco Stroke & Coat is a versatile ceramic glaze that functions as both a glossy underglaze and a decorative glaze, known for its heavily pigmented, viscous formula that allows for opaque coverage, intricate designs, and custom colors by intermixing. It can be applied to greenware or bisque, fired from cone 06 to cone 10, and is AP Certified non-toxic, food-safe, and dinnerware safe when fired correctly.

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Properties & Use

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• Versatility: Can be used for detailed brush strokes, solid color coverage, or as a "wash" for watercolor-like effects.

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• Color Intensity: Heavily pigmented and intermixable, creating custom shades and vibrant, opaque colors even when layered over other colors.

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• Application: Can be applied to wet clay (greenware), leather-hard clay, or bisque.

• Fired Finish: Fires to a glossy finish, even without a clear glaze, though one can be added for extra shine.

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• Color Movement: Colors stay where applied and do not "run" or move when placed next to each other, making them suitable for intricate designs.

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• Consistency: Offers consistent liquid color and fired results.

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• Safety: AP Certified non-toxic, food safe, and dinnerware safe.

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• Apply: Use a brush to apply the glaze to your ceramic piece.

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• Layer for Opacity: For a translucent effect, use one coat. For more opaque coverage, apply two or three coats, allowing each coat to dry until the shine is gone before applying the next.

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• Mix Colors: Intermix the stroke and coats to create a wide range of custom colors.

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• Coverage: Can NEVER be applied to the bottom of a piece due to its glaze-like glossy consistency which will fuse to the kiln shelf.

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Colored Slip

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• Colored slip is a liquid mixture of clay, water, and a coloring agent (like a Mason stain or oxide) used to add color, texture, or design to a ceramic piece while it is still in its wet or soft leather-hard stage. It can be applied by painting, splashing, dipping, or using slip-trailing techniques to create patterns, and can also be used as a base for other decorations like sgraffito (carving through the slip) or layering. Does not run like glaze.

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Application

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• Colored slip is applied to the ceramic piece when it is wet or, more commonly, leather-hard, can be applied to the bottoms.

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Decorating techniques

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• Slip trailing: Applying slip with a squeeze bottle to create raised patterns or designs.

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• Painting: Using brushes to paint decorative designs, similar to painting on canvas.

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• Texturing: Using objects like sponges or screens to press textures into a thick layer of slip.

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• Sgraffito: Applying a colored slip and then carving or cutting through it to reveal the contrasting clay body underneath.

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• Layering: Applying multiple layers of colored slips and carving through them to create depth.

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Mixing

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• Commonly slip is made from a dried out white clay body. Aiming for a stain/oxide to clay ratio.

• Most Mason Stains are added at a 5 - 6% to dry clay ratio (by weight) to avoid an oversaturation of color which can cause blistering during the final firing. Pastel stains can go up to 10%.

• Add the stain or oxide to the dry clay, next add water to the same level of clay in the container. Once saturated thoroughly, mix with an immersion blender. More water can be added after it has been mixed to achieve the desired consistency for the application.

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Mason Stains

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• Require a brushing medium and require far more testing than purchasing premade commercial underglazes. Any and all mason stains can be added to a brushing medium or a slip if you have had the education on how to best mix your own. Adding 5-7% stain to water on average by weight. 5~ grams of mason stain to 100 milliliters of water.

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Oxides

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• Naturally occurring minerals that can be used as a wash or a “stain” but also require far more testing than purchasing premade underglazes, using the colored slips provided in the handbuilding area at clay space or the oxides that are provided in the glazing area. Adding 5-7% stain to water on average by weight. 5~ grams of mason stain to 100 milliliters of water.

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Pre-approved Underglazes at Clay Space

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The Following is a list of preapproved underglazes ONLY to be used at Clay Space without the need to seek approval.
It is still recommended that you test new materials each time you put them in use. This does not include “glazes” from the same companies. Which do require the entire approval process for each glaze, many glazes won’t be approved by nature of their runny tendencies.

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Pre-approved lines:

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• Mayco Underglazes

• Amaco Velvet Underglazes

• Mayco Stroke and Coat - NEVER to be applied to the bottom of a piece

• Coyote Underglaze

• Duncan E-Z Stroke

The following must seek the approval process (Underglazes that have NOT been tested at Clay Space):

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• Speedball

• Kiwi

• Spectrum

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Always ask questions through your testing and learning process, have fun adding color!