Designing for Atmospheric Glazing

Because the glaze develops from the kiln atmosphere rather than from applied glaze, the preparation and design of work for salt and soda firing is different from standard glazing.

Slips Are Essential

Salt and soda on bare clay produce a thin, often pale result. To get rich colour and depth, potters apply slips before the first bisque firing. The slip interacts with the atmospheric sodium to create denser, more varied surfaces.

• Iron-rich slips produce warm ambers, oranges, and browns.
• Cobalt slips produce deep blues with the atmospheric glaze over them.
• White kaolin slips produce clean, crisp surfaces that the salt or soda glaze coats clearly.

The Orange Peel Texture

The signature orange peel texture of salt and soda glazing is caused by the sodium vapour depositing unevenly on the surface. The level of texture can be influenced by:

• Clay body texture: rougher surfaces produce more pronounced orange peel.
• Kiln placement: areas near the ports where sodium is introduced receive heavier deposition.
• Number of salt or soda applications: multiple smaller additions create more even coverage than one large addition.

Kiln Wear

Salt and soda slowly destroy kiln bricks over time because the sodium reacts with the silica in the brickwork, just as it does with the pots. Salt kilns are typically built with hard, dense bricks and are dedicated specifically to salt firing: you cannot use a salt kiln for standard oxidation or glaze firings without contaminating your work.

Explore More

The dedicated kilns required for salt and soda firing are lined with dense refractory brick to resist the corrosive effects of sodium vapour. Bernard Leach was instrumental in promoting salt glazing for studio use in the 20th century, and the technique was later introduced into American university ceramics programs, where it remains a valued part of the curriculum.

Reading Results More Accurately

• Check surfaces at multiple angles in natural light; orange-peel depth can be subtle.
• Compare port-facing and sheltered sides of the same form to understand deposition gradients.
• Note where slip thickness amplified colour so you can repeat successful prep.

Pro Tip

Log sodium introduction timing and amount by minute. Atmospheric glaze quality improves dramatically when additions are consistent, not improvised.