Ceramic Glazes


When working with ceramics, the final creation ends with a glaze. Ceramic and pottery glazes are liquid coatings applied to fired clay objects to add color, texture, and a protective finish. The glaze fuses to the surface of the pottery during a second firing, creating a glassy and durable coating. Here at Blick, we source a diverse range of glazes from top brands.


Factors to Consider When Selecting Glazes

  • Firing Temperature: To ensure optimal results, it is important to choose a glaze with a firing range that matches the clay’s firing range.
  • Clay Body: Consider the porosity, surface texture, and composition of the clay, as some glazes adhere better to certain types of clay bodies.
  • Desired Finish: Common glaze finishes include glossy, matte, satin, and crystalline.
  • Functionality: If your piece is meant to be food-safe, microwave-safe, or similar, double-check that your glaze meets the criteria.

Underglazes

Underglaze is essentially a type of paint designed for ceramic applications. While not strictly necessary, underglazes come in a variety of colors and are used to decorate your piece. You can even use sgraffito tools to scratch through a layer of underglaze and reveal the clay body.


Firing Process

  1. Apply underglaze to the unfired, dry clay piece. To achieve deeper color, apply 2-3 coats of underglaze.
  2. Once the underglaze is dry, place the clay piece in a kiln and bisque fire it to harden the clay body. Bisque firing refers to the first firing of a ceramic piece and it prepares the clay for glazing.
  3. When the piece cools, apply a layer of glaze (clear or colored) over the underglaze.
  4. Place the clay piece in the kiln once again. Glaze fire the piece to melt the glaze and fuse it with the clay and underglaze. This adds a final protective layer and completely seals the surface.

Firing Temperatures

  • Low-Fire Glazes: Low-fire glazes are commonly used for earthenware and mature around cone 06 to cone 04.
  • Mid to High-Fire Glazes: Mid to high-fire glazes are commonly used for stoneware and porcelain. These glazes mature around cone 5 to cone 10.

Testing Your Glaze

To ensure you’ve selected the right glaze, test a small sample before applying it to your ceramic pieces. Testing helps you understand how the glaze will interact with your specific clay body and firing conditions. Additionally, testing helps to visualize any special effects you may be trying out with the glaze. When layered, glazes can often create different visual effects and colors. Small batch testing is a great way to experiment with these techniques without sacrificing a large project.

Frequently Asked Questions