If you are new to using a pottery kiln, it will take you some time to grasp the fact that firing your artwork would require the use of a cone. Simply put, kilns aren’t fired to a given temperature but rather to a certain cone level. Understanding the cone level helps determine the right temperature and time required to fire a piece properly. It is more of a heat absorption technique as compared to increasing or decreasing the temperature.
How do cones work?
Cones are available in a range of numbers. Now, each of these cones corresponds to the temperature and heating rate combination that might cause the deformation of the cone. When the firing process starts, the cone stands at an angle of 8 degrees. When fired perfectly, the cone will achieve an angle of 90 degrees. Check whether the cone has less bending. If it does, the pottery piece is under-fired. If the angle surpasses the 90-degree mark, it states that the pottery work is over-fired.
Now, take a look at the numbers in these cones. The hottest cone is numbered 10 while it gets cooler, with 1 being the lowest temperature. However, 1 isn’t the coolest. It continues with 01, 02, and so on.
So, how does cone 5 differ from cone 6? Let us check it out!
Firing Temperature
Technically speaking, there isn’t much difference between cone 5 and cone 6. Even the temperature difference between them isn’t a major one. While cone 5 fires at 2118 degrees Fahrenheit, cone 6 tends to fire at 2165 degrees Fahrenheit.
Now, you might wonder, what about cone 06 and cone 05? Well, they fall well below the single-numbered cone category. Cone 06 fires at a much lower temperature compared to cone 6, and the same is applicable to cone 05 as well. For cone 05, the firing temperature is 1870 degrees Fahrenheit, while the firing temperature for cone 06 is 1798 degrees Fahrenheit.
In the pottery world, the placement of “0” ahead of a number represents “minus.” This means any firing cone with 0 placed ahead will have a lower firing temperature as opposed to single numbers.
Cone 5: Complete Detail
Cone 5 is also termed a middle-temperature cone. It is the lower temperature range required to fire most pottery stonewares, porcelains, and hobby art. Several potters are now moving from the use of cone 6 all the way down to the cone 5 levels. This helps with a considerable amount of energy saving which is about 40 degrees less.
Moreover, there is way less wear & tear within the electric kiln parts, which provides longevity and durability for the machine. As the kiln gets older, achieving the final few degrees with a particular cone can be a difficult task. This can lead to raked-up power bills.
Thankfully, most middle-temperature glazes available for potters are meant for the cone 5 to 6 range. Depending on the brand, most pottery glazes meant to be fired at cone 6 still tend to melt well. This is especially true due to the temperature holds that happen at the final stage of firing.
If your kiln is an old one or you plan to save on your energy bills, make sure you start with a test batch to check if it works or not. This is especially helpful with certain reactive glazes. Although several brands mention that they should be fired at the cone 6 temperature, most are over-fired at this level. With cone 5 firing, you can surely attain better results.
However, working through the maturity of clay bodies at a lower cone tends to be a tricky move. So, make sure you have the right cone to help you in your pottery escapades. A great choice for kiln firing is the Orton Cones Self-Supporting Pyrometric Cone 6. This pack of 25 cones has a fixed angle and mounting height to help you monitor the firing process.
Can You Fire Cone 6 Clay at Cone 5 Temperature?
Whether or not your clay can be fired at a lower cone temperature would depend on how you assess it. Take a look at the porosity and fired color to understand the clay body data. Firing a clay one cone lower helps achieve better glazing results with a visible difference. This is especially true for the interior part of the ceramic with a glassy & perfect look.
But, how does this happen? The key is slow-cool. This technique helps the glaze set better on the clay.
Similarities Between Cone 5 & Cone 6
Strictly speaking, Cone 5 & Cone 6 falls under the mid-fire range. However, most potters opt for the cone 6 firing level as it is easily achievable with generic electric kilns. The glazes used in mid-range options tend to work through the oxidation process. Here, oxygen tends to interact with glazes in order to create particularly bright colors.
So, it doesn’t necessarily matter whether you fire clay meant for cone 6 to cone 5 levels. The results would be fairly similar. Firing at cone 6 would get you a solid homogeneous and stony-colored look with a warmer tint. On the other hand, firing at cone 5 would get you bisque-like effects.
How to Achieve Cone 6 Maturity by Firing at Cone 5?
If you plan to achieve a perfect result with cone 5 firing when using cone 6, it is better to opt for the fire-and-hold process. All you need to do is fire the clay at cone 5 for the time frame mentioned by the manufacturer. Once the firing process is complete, the key is to hold the clay in the set temperature environment to achieve cone 6 effects.
Cone 5 | Cone 6 |
| Firing Temperature-2118oF | Firing Temperature-2165oF |
| Cone 5 Glaze Cannot Be Fired at Cone 6 (Can Lead to Cracking or Glaze Burning) | Cone 6 Glaze Can Be Fired at Cone 5 |
| More Porosity (When Cone 6 Glaze is Fired at Cone 5) | Less Porosity (When Cone 6 Glaze is Fired at Cone 5) |
| Bisque-Firing Effect | Homogenous & Stony-Colored with Warmer Tint |
Conclusion
Practically speaking, there shouldn’t be much difference between firing your pottery piece at Cone 5 or Cone 6. Although the final result would be a perfectly fine pottery piece that is fired to achieve permanency, there could be slight differences between the two. If you are someone who loves to experiment, you can achieve some amazing results with these two cone-firing choices!
