Mastering Underglaze: A Step-by-Step Guide to Test Tiles

Underglazes are a versatile medium for ceramic artists, allowing for a wide range of colors and effects. However, testing underglazes before committing to a large project is crucial to ensure desired results. This guide will walk you through the process of making underglaze test tiles, helping you achieve the perfect underglaze application for your ceramic pieces.

Before we dive into the process, let's briefly discuss why test tiles are essential. Underglazes can behave differently based on the clay body, glaze, and firing schedule. By creating test tiles, you can observe how the underglaze interacts with your specific materials and conditions, ensuring a successful outcome for your final pieces.

Preparing Your Workspace and Materials

Creating underglaze test tiles requires minimal setup. Here's what you'll need:

• Underglazes in various colors
• Test tile clay or scrap clay
• Rolling pin or slab roller
• Needle tool or scribe
• Brushes for applying underglaze
• Glaze and glaze brush
• Kiln and firing schedule

Creating Test Tiles

Start by preparing your test tiles. You can use leftover clay or specifically roll out test tile slabs. Aim for tiles around 2" x 2" to 3" x 3", ensuring they're thick enough to support the underglaze and glaze applications.

Once your tiles are rolled out, use a needle tool or scribe to score and cut them into the desired sizes. Clean up the edges with a trimming tool or needle tool to remove any sharp points or rough areas. Allow the tiles to dry to the leather-hard stage before proceeding.

Applying Underglazes

Now that your test tiles are ready, it's time to apply the underglazes. Begin by mixing each underglaze color with a small amount of water to achieve a smooth, paint-like consistency. The ideal consistency will vary depending on the brand and type of underglaze, so adjust the water content as needed.

Using a dedicated brush for each color, apply the underglaze to the test tiles. Vary the application method to test different effects, such as thin washes, thick applications, or sgraffito techniques. Allow the underglaze to dry completely before proceeding to the next step.

Glazing and Firing

After the underglaze has dried, it's time to apply the glaze. Choose a clear or transparent glaze to allow the underglaze colors to show through. Apply the glaze evenly over the underglaze, ensuring full coverage. Be careful not to apply too much glaze, as this can cause crawling or other firing issues.

Once the glaze has dried, your test tiles are ready for firing. Follow your usual firing schedule, ensuring the tiles reach the appropriate temperature for both the underglaze and glaze to mature properly. Allow the tiles to cool completely in the kiln before unloading.

Evaluating Results

After firing, carefully examine your test tiles for any issues, such as crawling, blistering, or color shifts. Make notes on each tile, recording the underglaze color, application method, and any observations. This information will be invaluable when selecting underglazes for your final pieces.

Compare the fired results to your initial expectations and adjust your underglaze application or selection as needed. Repeat the process with any new underglazes or application methods you'd like to test.

Creating underglaze test tiles is an essential step in ensuring successful results for your ceramic projects. By taking the time to test underglazes in your specific working environment, you'll gain valuable insights into their behavior and make more informed decisions about their use in your final pieces. Happy testing, and may your underglaze experiments bring you countless creative possibilities!