For ceramicists, kiln firing can often feel like a bit of a gamble. Despite diligently following all safety protocols, there is always a possibility of something unexpectedly going wrong. One of the most common – and potentially dangerous – mishaps that can occur when firing glazed pieces is glaze fusion, or when two glazed pieces of ceramic touch in the kiln and fuse together. Today, we’re discussing exactly what happens when two glazed pieces touch in the kiln and how you can avoid potential mishaps.
The Consequences of Two Glazed Pieces Touching
It’s important to realise that most pieces will not be ruined if two glazed pieces touch in the kiln. The outcome of the firing largely depends on the type and amount of glaze applied to both pieces, as well as the temperature of the kiln and how long both pieces were fired for. Generally speaking, two glazed pieces touching one another in the kiln will result in a weakened, uneven finish on both pieces.
Although glaze fusion may not always completely ruin your work, it can have serious long-term consequences. Two fused pieces will be weaker than before and more prone to breaking, even after cooling. In some cases, a single glazed piece may look fine on the surface, but if you apply pressure or flex the piece a crack will appear.
How to Avoid Glaze Fusion
The easiest way to avoid glaze fusion is to make sure that all ceramic pieces are thoroughly dry before placing them in the kiln. Although this can be difficult to achieve in humid environments, using a quality dehumidifier can help to reduce moisture levels in closed spaces. Additionally, make sure to double-check placement and spacing of all glazed ceramic pieces in the kiln.
Watching glaze colours is also a great way to check for potential fusion between two pieces. If your pieces contain coloured glazes, check for the presence of two distinct hues throughout the firing cycle; if two hues mix together, it’s likely that two glazed pieces are touching.
The Benefits of Glaze Fusion
Despite the trade-offs discussed above, glaze fusion can also have its advantages. By fusing two pieces together, an artist can create unique lines and patterns on a single piece. Additionally, some potters seek out glaze fusion as an intentional way to create textural effects on their work.
Factors That Affect Glaze Fusion
Aside from checking if two glazed pieces are touching in the kiln, there are other factors which could increase the risk of glaze fusion during a firing. These include: high firing temperatures, high quantities of glaze being applied, unventilated kiln environments, and an improper understanding of certain glazes.
Tips for Safely Firing Glazed Pieces
When it comes to safely firing glazed pieces, one of the most important considerations is using the correct temperature for the glaze you are using. Each glaze has an optimum temperature range for optimal results – usually it’s best to stick to the lower end of that range. Additionally, make sure to ventilate your kiln regularly – this will help reduce heat build-up and eliminate the risk of accidently fusing two pieces together.
Troubleshooting Common Kiln Firing Issues
It is also important to understand how to troubleshoot common kiln firing issues. If you suspect two glazed pieces have fused together, you can turn off the kiln and wait for it cool before attempting to separate them. However, it is not recommended to open the door and inspect the individual pieces from within. Additionally, if you notice any discoloration on glaze surfaces – this could be a sign of over-firing.
The Dangers of Kiln Firing with Glazes
Although glaze firing is a popular and rewarding ceramic technique, it’s important to remember that it comes with some safety risks. Poor ventilation in a kiln can cause heat build-up and inadvertent fusion between pieces, creating a dangerous situation. Always make sure to read safety instructions and follow your manufacturer’s instructions when operating your kiln.
What is the Best Kiln Temperature for Firing Glazed Pieces?
The best temperature for firing your glazed pieces depends on the types of glazes and clay bodies you’re using. Most glazes will require a minimum firing temperature of about 1260°C (2300°F). However, some may require temperatures up to 1300°C (2370°F) or higher. It is best to consult the manufacturer’s instructions for exact guidelines.
How to Clean Up After a Glaze Fusion Incident
If two glazed pieces have accidentally fused together in the kiln, it is important to take steps to repair them properly. It is always best to let the fused pieces cool completely before attempting any repairs. Wear safety goggles and protective gloves while separating any fused pieces – they can be sharp and may contain glass shards. You may also find it easier to use ceramic tools such as needle nose pliers or cutters. Make sure to properly dispose of any broken or discarded parts.
Although not always preventable, accidents like glaze fusion can create serious safety hazards when working with high temperatures and delicate materials. Hopefully this article has provided you with insight into what happens if two glazed pieces touch in the kiln – and how you can avoid potential problems more safely.
