Shino & Cooling: Time Written in the Glaze

In ceramics, the final moments of a firing are often the most decisive. Long after the kiln has reached its peak temperature, the cooling process quietly shapes the surface of a glaze. Subtle variations in how fast a piece cools can transform both color and texture in unexpected ways. In this experiment, both cups were glazed with the same layers of two different Shino glazes. Placing each cup in a similar position within the kiln but in two different firings, I was able to obtain a more empirical confirmation of how changes in the cooling cycle affect these Shino glazes.

After reaching peak temperature, one cup was left to cool naturally inside the kiln. The kiln I use cools relatively quickly, taking less than a day to return to room temperature. For the second cup, I intervened during the cooling phase. As the temperature dropped, I brought the kiln back on and held it at around 1030°-980ºC for approximately five hours before allowing it to continue cooling. This single variation—introducing a controlled hold during cooling—was enough to produce strikingly different results.

Stoneware cup #1 with layered Shino glazes: cooled at natural speed

Color: from clarity to complexity

The differences are immediately visible. The naturally cooled cup (visible above) presents a clear and direct palette: warm reddish-orange where the Shino glaze is thin, and bright, opalescent white where it is applied more thickly. The transitions are clear and relatively uniform.

On the other hand, the slow-cooled cup (visible below) develops a far more complex surface. In areas where the glaze is thin, the reds deepen into browns and muted tones, often accompanied by subtle metallic sheens. These surfaces feel less uniform, more layered, as the glaze had time to reorganize itself during the cool phase.

Part of this effect may be linked to slight variations during the hold. At one point, the temperature dropped closer to 980°C, and I have observed that this range can encourage browner, more metallic tones in thinner applications of my Shino. When held consistently closer to 1030°C, these areas tend to remain more vividly red—though this is something I am still in the process of confirming.

Thickness and transformation

For me, the most fascinating differences appear in areas where the glaze is applied more thickly. On the naturally cooled cup, these whitish areas remain bright, opaque and creamy. The surface feels rather clear and defined, with little visible movement. On the slow-cooled cup, however, these same areas become far more active. The surface develops warm tones of pink, orange, and brown, sometimes accompanied by a delicate metallic lustre that shifts subtly in the light. It is as though the glaze has come alive during the extended cooling, revealing hidden variations that remain dormant in a faster cycle.

Time as a material

What is happening here is not entirely straightforward. Rather than thinking of iron or other oxides “moving” through the glaze, it may be more accurate to consider that, given time at certain temperatures, these elements are able to reorganize themselves—forming different crystalline structures that alter the color and surface of the glaze.

In this sense, the cooling cycle becomes a material in its own right. By holding the kiln within specific temperature ranges, one allows the glaze to evolve, to settle into different states, revealing qualities that would otherwise remain unseen.

Shino cup #2: slow-cooled for 5 hoursat 1030ºC

An ongoing exploration

This experiment is part of a broader exploration into how time, temperature and material interact within the kiln. The process is not entirely predictable. Each firing offers new variations, new surfaces and new questions. For me, that uncertainty is part of the appeal. It transforms each piece into a record of a specific moment—a balance between control and chance, between intention and discovery.

Below you may wish to explore selection of my recent work.