When it comes to firing ceramics, many potters grapple with the decision of whether to fire within a cone 5 temperature range or within cone 6 temperature range. There are pros and cons associated with firing to each cone, and both have implications when it comes to the successful and consistent creation of ceramic art. In this article, we’ll discuss the differences between cone 5 and cone 6 ceramics, the pros and cons of firing to each cone, which glazes are best for each, best kiln temperatures for success, and tips for adjusting for specific results.
What is the Difference Between Cone 5 and Cone 6 Ceramics?
Cone 5 and cone 6 ceramics are two types of ceramic clays fired in kilns to give them their finished properties. The clay is fired at different temperatures to create, harden, and finish the materials. Cone 5 is a higher temperature range than cone 6, with the maximum range of cone 5 falling at around 2232°F (1223°C) and the maximum range of cone 6 resting at 2022°F (1113°C) – making cone 6 more of a mid-range firing temperature.
Pros and Cons of Firing to Cone 5
The most positive aspect of firing ceramic clay in the Cone 5 range is that it works with a variety of ceramic clays. Clays that are good for working with earthenware clay like porcelain or white stoneware will generally fire up to Cone 5 with no problems. The downside is that Cone 5 is a very high temperature and not all clay bodies will be able to tolerate it – especially those with high amounts of grog or coarse particles. You’ll want to make sure you check the temperature recommendation on your clay body label before firing.
Pros and Cons of Firing to Cone 6
The advantage to firing at Cone 6 over Cone 5 is that it provides you with more time and less stress. Cone 6 requires a lower heat than Cone 5, which means that it’s possible to keep your pieces in the kiln longer without fear that they’ll over-fire. This can be especially important if you’re trying to do intricate glaze patterns such as celadons, copper flashing, and crystalline glazes – all of which require extended exposure to heat.
What Glaze Should I Use for Firing at Cone 5 or 6?
When looking for a glaze to use for your Cone 5 or 6 pieces, use a cone chart as your guide. Glazes typically come in a range of glaze temperatures, so make sure you use one that matches up with your desired firing cone. For example, if you want to fire your piece at Cone 6, you’ll want a glaze that’s rated at Cone 6 or higher.
What is the Best Kiln Temperature for Firing at Cone 5 or 6?
The ideal temperature for firing at Cone 5 or 6 will vary depending on your kiln type, the clay you’re using, and what results you’re looking for. Generally, for high-fire porcelain or white stoneware shells fired at Cone 5, most kilns will hold around 2232°F (1223°C) for 12-15 minutes. For earthenware and salt glazes, temperatures between 1848°F (1010°C) to 2022°F (1113°C) are best.
Tips for Firing to Cone 5 or 6
- Make sure your kiln has enough airflow in order to properly vent it when you’re firing.
- If you’re using a new glaze, make sure you test it beforehand on a piece of clean scrap clay before using it on your final pieces.
- If glaze bleeds occur and cause unwanted problems, try reducing the time the piece spends in the kiln. This will reduce the amount of heat the piece is exposed to which in turn should reduce the risk of glaze runoff.
- Be aware of any excess moisture that may be left over on your pieces prior to firing. This will evaporate when it hits the kiln walls causing hotspots in your kiln.
- Vent your kiln until it cools down to around 1093°F (592°C) before opening.
- Always wear appropriate safety equipment when firing ceramics.
Common Mistakes When Firing at Cone 5 or 6
- Not following manufacturer’s instructions regarding temperature or duration of firing.
- Using improper clay bodies or non-kiln safe glazes.
- Not testing glazes on scrap clay prior to using on desired piece.
- Leaving moisture on pieces prior to firing.
- Opening kiln too rapidly when cooling down products.
- Firing too quickly resulting in various defects in pieces.
How to Adjust Your Kiln Temperature for Specific Results
When it comes to adjusting your kiln temperature for desired results, the coning process is the best way to go. This process involves picking an appropriate coning temperature and adjusting your heat accordingly throughout the course of firing. Make sure that when firing, you pay attention to any warnings that appear on your kiln controls and adjust your temperature as quickly as possible if needed. It’s also important to monitor the outer walls of your kiln while firing – they should be clean and free of soot or residue.
What Clay is Best Suited for Firing at Cone 5 or 6?
The type of clay best suited for firing at cone 5 or 6 will depend on your desired results. For example, if you’re looking for high-fire porcelain or white stoneware shells, porcelain and white stoneware clays will fire well at cone 5. Earthenware clays such as red earthenware, buff earthenware, terracotta, and some yellow earthenware are better suited for firing at cone 6 or lower. Additionally, some stonewares such as grogged stoneware can fire up to cone 6 depending on their makeup.
From casual potters crafting unique creations to professional potters producing consistent results, firing ceramic objects to cone 5 or 6 can help bring your imagination and creations alive. While there are pros and cons associated with each type of firing, understanding which glazes work the best, adjusting kiln temperatures correctly, and selecting the right clay body can help you achieve great results.
