How to Get Rid of Bubbling in Glaze for Pottery

Glazing is one of the most exciting parts of pottery—it’s when your piece truly comes to life with color, texture, and finish. But nothing is more frustrating than opening the kiln and seeing bubbles in your glaze. Glaze bubbling can ruin an otherwise beautiful piece, making the surface rough, pitted, or uneven.

If you’ve been dealing with glaze bubbles, don’t worry! This guide will walk you through the common causes of bubbling and provide effective solutions to help you achieve a smooth, flawless glaze finish.

What Causes Glaze Bubbling?

Bubbling in glaze typically happens due to trapped gases escaping during the firing process. These bubbles can form under the glaze or within it, creating small craters or pinholes on the surface of your pottery. Some of the most common causes include:

• Air pockets in the clay: If air is trapped in the clay body, it can create gases that push through the glaze during firing.
• Organic materials burning out: If your clay contains organic materials or impurities, they release gases as they burn off in the kiln.
• Glaze applied too thickly: Thick layers of glaze trap gases, making it difficult for them to escape properly.
• Improper firing schedule: Firing too quickly or at the wrong temperature can prevent gases from escaping evenly, leading to bubbles.
• Incompatible glaze and clay body: Some glazes don’t adhere well to certain clay bodies, causing instability and bubbling.

Now that we know why bubbling happens, let’s explore how to fix it!

How to Prevent Glaze Bubbling

1. Apply the Right Thickness of Glaze

One of the biggest mistakes potters make is applying glaze too thickly. Thick glaze layers trap gases, which results in bubbling.

Solution:

• Dip, brush, or spray your glaze in thin, even layers.
• If dipping, keep it to 1-2 dips and allow the first layer to dry before adding another.
• Use a glaze thickness gauge or check the glaze’s specific gravity to ensure consistency.

2. Wipe Down Your Bisqueware

Dust, oils, or residue on the surface of your bisqueware can create bubbling by interfering with the glaze’s ability to adhere properly.

Solution:

• Before glazing, use a damp sponge to wipe down your bisque-fired pottery.
• Avoid touching the surface too much with your hands to prevent oil transfer.
• If necessary, use compressed air to remove fine dust particles.

3. Slow Down the Firing Process

Firing too quickly can prevent gases from escaping properly, leading to bubbling.

Solution:

• Use a slower firing schedule, especially during the early stages of the glaze firing.
• Consider holding at a mid-range temperature (such as 1100-1300°F) to allow gases to escape before the glaze fully melts.
• If using an electric kiln, experiment with a longer hold at peak temperature to let bubbles smooth out.

4. Adjust Your Clay and Glaze Compatibility

Sometimes, the problem is the clay body and glaze not working well together. Some clay bodies contain impurities that release gases at different temperatures.

Solution:

• Test different glaze and clay body combinations before committing to a large batch.
• If you’re experiencing persistent bubbling, try a different clay body with fewer impurities.
• Use a glaze fit test to see if your chosen glaze works well with your clay.

5. Refire the Piece

If bubbling has already occurred, you might be able to save your piece by refiring it.

Solution:

• Fire the piece again at a slightly higher temperature to smooth out any remaining bubbles.
• If needed, lightly sand down the bubbled areas before refiring.
• Apply a thin additional layer of glaze before refiring to help fill in minor imperfections.

Final Thoughts: Achieving a Smooth Glaze Finish

Bubbling in glaze can be frustrating, but with the right techniques, you can prevent it and achieve beautifully smooth results. By applying thinner glaze layers, wiping bisqueware clean, slowing down your firing process, ensuring clay and glaze compatibility, and refiring if needed, you can eliminate bubbling for good.

Glazing is an art, and troubleshooting is part of the journey. Keep experimenting, adjusting your methods, and refining your process to create stunning, bubble-free pottery every time!