How are Cone 05 vs Cone 5-6 different? Which one should I choose for my project?
For those new to the world of ceramics, one thing that often causes the most confusion is "firing temperature," also known as Cone, which measures the temperature in the kiln. This is especially true for confusing numbers like Cone 05 and Cone 5-6. Many people see these numbers and think they should be similar, but in reality, the single "0" changes everything entirely, including the temperature, clay body, and glaze results.
Today, Pottery Clay will take everyone on a deep dive into how these two levels differ.
A Single "0" Changes Everything
The first golden rule for potters to remember is that "a 0 in front of the number is like a minus sign." The higher the number after the 0, the lower the temperature. Conversely, for numbers without a 0, the higher the number, the higher the temperature.
Therefore, Cone 05 falls into what we call Low-Fire, which uses an average temperature of only about 1030-1045°C. In contrast, Cone 5-6 moves up to the Mid-Fire range, requiring high heat of approximately 1190-1220°C.
Firing at Cone 05 (Low-Fire) gives vibrant colors, but the clay body remains breathable.
Firing at Cone 05 is often used with earthenware clays, or the familiar red clay known as terracotta. The advantage of low-firing is that the heat, which is not too high, does not destroy the color-giving minerals in the glazes. This results in brightly colored, vibrant glazed pieces that are easy to control and offer many unusual shades. It also saves electricity and helps prolong the lifespan of the kiln elements.
However, a significant limitation of Cone 05 pieces is that the clay at this temperature does not vitrify completely. The clay body remains highly porous and can absorb water. If used for liquids or food, the clay might absorb moisture and easily develop mold. Therefore, low-fired pieces are often preferred for decorative items like garden figurines, wall tiles, or display dishes, rather than for daily practical use.
Firing at Cone 5-6 (Mid-Fire) for Glass-like Strength, Ideal for Functional Ware
When the temperature is increased to Cone 5-6, the clay body changes to stoneware or certain types of porcelain. At a temperature of approximately 1200°C, minerals and silica in the clay undergo vitrification, resulting in a dense, strong, and durable body that is resistant to scratching and breakage.
Crucially, it is "non-absorbent," making it safe for food containers (Food Safe) and suitable for use in microwaves and dishwashers with peace of mind.
While the colors of Cone 5-6 may not be as vibrant as those from low-firing, due to some primary colors being destroyed by high heat, what you gain are glazes that react intensely with the clay body. This creates subtle, deep, and dimensional flowing, crystalline, or shimmering effects, which are highly favored by artists and cafes today.
A crucial rule for using Cone 05 and Cone 5-6 glazes is: Never fire Cone 05 glazes at Cone 5-6 temperatures, as the glaze will melt and flow, damaging the kiln shelves.
Conversely, if you fire Cone 5-6 glaze at Cone 05, the glaze will not melt and will leave a dry, sandy texture. Therefore, before applying any glaze, always check the labels on both the clay and glaze bottles to ensure that the "Cone numbers match" for the best possible results.