What are the risks of double glazing pottery?

Double glazing pottery involves applying two layers of glaze to ceramic pieces, but it comes with certain risks that can affect the final outcome. Understanding these risks is crucial for potters who want to achieve the desired aesthetic and functional results.

What is Double Glazing in Pottery?

Double glazing in pottery refers to the process of applying two layers of glaze on a ceramic piece. This technique can enhance the visual depth and texture of the pottery, creating unique and vibrant finishes. However, it requires careful consideration of various factors to avoid potential issues.

Risks of Double Glazing Pottery

1. Glaze Crawling

Glaze crawling occurs when the glaze pulls away from the surface during the firing process, leaving bare patches. This can happen if the underlying glaze is not properly adhered to the pottery or if the second glaze layer is incompatible with the first.

Prevention Tips:

• Ensure the first glaze is thoroughly dry before applying the second layer.
• Test compatibility of glazes on a sample piece before applying to the final work.

2. Glaze Running

Glaze running is when the glaze melts excessively during firing and drips off the pottery, leading to uneven coverage and potential kiln damage. This is more common when using high-fluidity glazes.

Prevention Tips:

• Apply thinner layers to control the flow of the glaze.
• Use glazes with similar melting points to ensure even melting.

3. Pinholing and Blistering

These defects appear as small holes or blisters on the glaze surface, caused by trapped gases escaping during firing. Double glazing can exacerbate this issue if the layers are too thick or if the firing schedule is not optimized.

Prevention Tips:

• Fire the pottery slowly to allow gases to escape gradually.
• Ensure the bisque firing is thorough to remove all organic materials.

4. Incompatibility of Glazes

Not all glazes work well together. Incompatibility can lead to issues like glaze cracking or crazing, where the glaze surface develops fine cracks. This often results from different expansion rates between the glazes.

Prevention Tips:

• Use glazes from the same manufacturer or series to ensure compatibility.
• Test glazes on small test tiles before applying to larger pieces.

Practical Examples and Case Studies

• Case Study 1: A potter experienced severe glaze crawling when using a high-gloss transparent glaze over a matte base. By adjusting the firing temperature and using a compatible base glaze, the issue was resolved.
• Case Study 2: In a pottery class, students learned to avoid glaze running by applying thinner layers and maintaining a consistent firing schedule, resulting in more uniform finishes.

People Also Ask

What is the best way to apply double glazing to pottery?

The best way to apply double glazing is to ensure the first layer is completely dry before applying the second. Use a brush or spray to apply thin, even coats, and test on a sample piece to ensure compatibility.

How can you fix glaze crawling after firing?

Fixing glaze crawling after firing can be challenging. One approach is to refire the piece after applying a thin layer of compatible glaze to the affected areas. However, this may not always yield perfect results.

Can double glazing affect the durability of pottery?

Double glazing can potentially affect pottery’s durability if the glazes are not compatible, leading to crazing or cracking. Ensuring glaze compatibility and proper application can mitigate these risks.

Why do some potters prefer single glazing over double glazing?

Some potters prefer single glazing to avoid the complexities and risks associated with double glazing, such as crawling, running, and incompatibility. Single glazing can also be more cost-effective and time-efficient.

What firing schedule is recommended for double glazed pottery?

A slow and controlled firing schedule is recommended for double glazed pottery to prevent defects. Start with a slow ramp to allow gases to escape, followed by a steady increase to the target temperature.

Conclusion

Double glazing pottery offers the potential for stunning visual effects, but it comes with inherent risks such as glaze crawling, running, and incompatibility. By understanding these risks and taking preventive measures, potters can achieve successful results. For further exploration, consider learning about different glazing techniques and how they can enhance your pottery projects.