To use clear glaze effectively, you typically apply multiple thin coats to your ceramic piece, allowing each coat to dry before applying the next, to achieve a uniform and lustrous finish. Here's a breakdown of the process:
1. Preparation is Key
- Ensure bisque firing: Your ceramic piece must be bisque-fired before applying any glaze. This hardens the clay and allows the glaze to adhere properly.
- Clean the piece: Thoroughly clean your bisque ware to remove any dust, dirt, or oils. This can be done with a damp sponge. Even fingerprints can cause glaze defects.
- Wax resist (Optional): If you're applying clear glaze over another glaze or a specific design, use wax resist to prevent the clear glaze from adhering to those areas.
2. Application Methods
There are several common methods for applying clear glaze:
- Brushing: This method involves applying the glaze with a soft-bristled brush. It's good for detail work and smaller pieces.
- Multiple Coats: Brushing often requires 2-3 coats, sometimes more, depending on the glaze and desired thickness.
- Direction: Apply each coat in a different direction (e.g., horizontal then vertical) for even coverage.
- Dipping: Dipping involves submerging the entire piece (or a section of it) in the glaze. This method is quick and efficient for uniformly shaped objects.
- Even Coverage: Ensure even coverage by dipping quickly and smoothly.
- Thickness Control: Control the thickness of the glaze by adjusting the dipping time.
- Pouring: Pouring involves pouring the glaze over the piece. It's suitable for larger pieces or complex shapes that are difficult to dip.
- Spraying: This involves using a spray gun to apply the glaze. It provides a very even and thin coating.
- Ventilation: Requires proper ventilation and safety equipment.
- Thin Coats: Spraying usually requires multiple thin coats.
3. Applying the Glaze
- Stir the glaze thoroughly: Before applying, stir the glaze well to ensure that it is evenly mixed. Glazes tend to settle over time.
- Apply thin coats: This is crucial. Thick coats can lead to running, dripping, and other glaze defects.
- Let each coat dry: Allow each coat to dry completely before applying the next. This prevents the glaze from running and ensures even coverage. Drying time varies depending on the humidity and the glaze itself.
- Number of Coats: Typically, 2-3 coats are sufficient, but follow the specific instructions for your glaze.
4. Troubleshooting
- Crawling: If the glaze pulls away from the surface during firing, it's called crawling. This can be caused by dust, oil, or too thick of a glaze application.
- Running: If the glaze runs down the piece during firing, it's likely applied too thickly.
- Pinholes: Small holes in the glaze surface can be caused by trapped air or impurities.
- Cloudy Glaze: Can sometimes result from underfiring.
5. Firing
- Follow Manufacturer's Instructions: Always fire the glazed piece according to the glaze manufacturer's instructions. Firing temperature is critical for achieving the desired results.
- Proper Ventilation: Ensure proper ventilation in your kiln room.
Summary
Using clear glaze involves careful preparation, application of multiple thin coats allowing each to dry, and firing according to the glaze's specifications. Proper technique ensures a smooth, even, and lustrous finish that enhances the underlying clay or decorative elements.
