What are common mistakes when double glazing pottery?

Double glazing pottery is a technique that can enhance the aesthetic and functional qualities of ceramic pieces, but it comes with its own set of challenges. Common mistakes when double glazing pottery include issues with glaze application, firing temperatures, and glaze compatibility. Understanding these pitfalls can help potters achieve better results and avoid costly errors.

What is Double Glazing in Pottery?

Double glazing refers to the application of two layers of glaze on a pottery piece. This technique can create unique visual effects and textures, but it requires careful handling to ensure that both layers adhere properly and do not cause defects in the final product.

Common Mistakes When Double Glazing Pottery

1. Incorrect Glaze Application

One of the most frequent errors in double glazing is improper application of the glaze layers. Applying the second glaze too thickly can lead to issues such as:

• Running and Dripping: Excess glaze can run during firing, causing unsightly drips or pooling at the base.
• Crawling: This occurs when the glaze pulls away from the surface, often due to uneven application or contaminants.

To avoid these problems, ensure that each layer is applied evenly and is allowed to dry thoroughly before adding another.

2. Incompatible Glazes

Using glazes that are not compatible with each other can result in undesirable effects such as:

• Cracking: Different expansion rates between glazes can cause cracking or crazing.
• Color Bleeding: Incompatible glazes may bleed into each other, distorting colors and patterns.

Always test glazes together on a small sample piece before applying them to your final work.

3. Incorrect Firing Temperatures

Firing at the wrong temperature can ruin a double-glazed piece. Common issues include:

• Underfiring: This can leave the glaze underdeveloped and dull.
• Overfiring: This can cause the glaze to melt excessively, leading to defects like pinholing or blistering.

Consult the manufacturer’s guidelines for both glazes and ensure your kiln is properly calibrated.

4. Poor Surface Preparation

The surface of the pottery must be clean and free of dust or oils before glazing. Any contaminants can prevent the glaze from adhering properly, leading to defects such as crawling or pinholing.

5. Inadequate Drying Time

Rushing the drying process between glaze applications can cause the layers to mix or fail to adhere correctly. Allow sufficient time for each glaze layer to dry completely before applying the next.

How to Avoid Double Glazing Mistakes

• Test Glazes: Always conduct tests on small pieces to check for compatibility and desired effects.
• Monitor Thickness: Use a thickness gauge to ensure even application of each glaze layer.
• Follow Firing Schedules: Adhere to recommended firing schedules for each glaze type.
• Maintain Clean Surfaces: Ensure all pottery surfaces are clean before glazing.
• Allow Adequate Drying Time: Be patient and allow each layer to dry thoroughly.

Practical Examples of Successful Double Glazing

Consider a potter who uses a base glaze of a matte white and a top glaze of a translucent blue. By applying the white glaze thinly and allowing it to dry completely before adding the blue, the potter achieves a beautiful layered effect without any running or bleeding.

People Also Ask

What Causes Glaze to Crawl?

Glaze crawling is typically caused by poor surface preparation or incompatible glaze layers. Ensuring clean surfaces and testing glazes for compatibility can help prevent this issue.

How Can I Fix Pinholing in Glaze?

Pinholing can often be resolved by adjusting firing temperatures or ensuring the glaze is applied at the correct thickness. Sometimes, a slower firing schedule can help eliminate these defects.

Why Do Glazes Crack After Firing?

Cracking or crazing occurs when there is a mismatch in the thermal expansion rates of the clay body and glaze. Testing for compatibility and adjusting glaze formulations can mitigate this problem.

Can Double Glazing Be Used on All Pottery?

While double glazing can be used on most pottery, it is not suitable for all types. Some clay bodies may not tolerate the additional stress of multiple glaze layers, so testing is essential.

How Do I Choose the Right Glazes for Double Glazing?

When selecting glazes, consider their firing temperatures, chemical compositions, and visual effects. Testing combinations on small samples before applying them to larger pieces is crucial.

Conclusion

Double glazing pottery offers exciting opportunities for creative expression, but it requires careful attention to detail. By understanding and avoiding common mistakes like incorrect glaze application, incompatible glazes, and improper firing, potters can create stunning, durable pieces. Always prioritize testing and patience in your process to achieve the best results.

For further exploration, consider learning about glaze chemistry or experimenting with different firing techniques to enhance your pottery skills.