The process of glazing ceramics involves applying a liquid glaze to the surface of pottery to achieve decorative and functional qualities. However, applying glaze before firing, without the proper firing process, can lead to undesirable outcomes. Let’s explore what happens if you glaze before firing and why it’s crucial to follow the correct sequence in pottery making.
Incomplete Transformation
Glaze is composed of various minerals that, when fired to specific temperatures, melt and fuse together to form a glassy surface. If glaze is applied to pottery before firing, these minerals won’t fully transform, resulting in a fragile and incomplete layer that may easily chip, crack, or peel off.
Weak Adhesion
Firing clay and glaze together is essential for proper adhesion. When glaze is applied to raw clay before firing, it lacks the porous surface that makes it adhere effectively during the firing process. This can lead to poor glaze adhesion, flaking, and an overall unsatisfactory appearance.
Glaze Defects
Glaze applied before firing can result in defects such as crawling, where the glaze pulls away from the clay, leaving bare spots. Other issues, like pinholing or blistering, may also occur due to the incomplete transformation of glaze minerals.
The Proper Sequence
To achieve successful glazing results:
- Apply glaze to bisque-fired pottery, which is clay that has been fired once without glaze.
- Follow recommended glaze application techniques to achieve desired effects.
- Fire the pottery to the appropriate temperature for the glaze to fully melt and fuse.
Conclusion
Applying glaze before firing may seem like a shortcut, but it can lead to weak adhesion, glaze defects, and incomplete transformation. To create durable, beautiful, and functional ceramic pieces, always follow the proper sequence of applying glaze to bisque-fired pottery and firing it to the appropriate temperature. This approach ensures that your pottery emerges from the kiln with the desired finish and integrity.