How Do You Mix Underglazes / Tips to Mix Underglazes

The process of mixing your own unique underglaze colors can be exciting. We’ll walk you through what materials and tools are needed to get started on making your own colors and shades of underglaze. Also provide some helpful tips that can make the process easier for you to start experimenting with different color combinations of underglazes to make your pottery even more unique looking. Let’s get started.

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Underglaze: What You Need to Know

Before we begin, I will go over the objective of underglaze. While underglazes do not have the same ingredients as paint, they are used in the same way to decorate the surface of the pottery. They are not meant as a substitute for glazing.

Underglazes contain a lot of Colorants a little clay and may contain CMC or Veegum, or both. The amount of clay, CMC, or Veegum depends on the underglaze manufacturer. Also, a little Frit (mixture of silica and flux), to help the underglaze fuse to the pottery. The underglaze does not create a non-porous seal on pots when fired in a kiln. Clear glaze must be applied to seal the surface of your underglaze. When you fire the clear glaze, the ingredients melt together to form a glass layer. For more detailed information on underglaze, check out this post Underglazing Pottery | Glazing Tips Tools and Ideas

What You Need to Mix Underglaze

• 2 or more Underglazes
• Containers
• Measuring spoons
• Test pieces (Greenware or Bisqueware)
• Distilled water
• Brushes
• Rotery tool (optional)

Step #1: Choose the Shade of Underglaze

To begin, choose the underglazes you wish to mix together. When it comes to blending colors of underglaze, you can stir up some new colors. For instance, if you mix red into yellow, you may end up with a cool shade of orange as an outcome.

Mixing underglazes together is different from Mixing paints. You have to see what color you get after it’s fired in the kiln. It’s important to know that some underglaze colors when mixed together just muddy up after they are mixed. That’s why it’s important to mix small amounts together at a time.

Don’t limit yourself just yet; there’s room for creativity when experimenting. For example, try adding a white to make your colors more pastel or a touch of black to create a sudden or dramatic change based on what color you are mixing in.

Step#2 Mixing Your Underglazes

You need to measure out the amount of underglaze you are mixing. A good way to measure out your underglazes colors would be to blend them in ratios, like 1 part of one color to 6 parts of another, 2 to 6, or 3 to 6, and so on. For example 1 teaspoon of red to 6 teaspoons of yellow. Or 1 gram of red to 6 grams of yellow which may create a cool shade of orange. You can also do 50-50 or 40-60 and so on.

Measuring out the underglazes allows you to duplicate the unique color you just created. If you run out of a specific color while decorating, making another batch will be tricky if you didn’t measure the underglazes because you may not get the color to match the last batch.

When mixing these small batches of underglazes together you can use a detail brush. Or you can use a rotary tool with a disc attachment.

Adding water

You can mix distilled water in with the underglaze to thin it out and mix your colors together. Be careful not to add too much water at a time. It’s best to add just a little and mix well before adding any more. It’s always easier to thin out your underglaze gradually than it is to wait for the water to evaporate. 

You want to use distilled water because you don’t know what other minerals or impurities are in the tap water and how it will react with the underglaze. Distillation boils away the impurities to make it less likely to react with the underglaze’s ingredients.

Watercolor underglazes

Watercolor underglazes look best on bisque-fired pottery because of how they absorb into the pores of the ceramic material. Therefore, you will use a generous amount of water from 1 part underglaze to 20 parts of water as the general guide. 

The amount of water to underglaze shows you a general rule, but how much water is used depends more on what you hope to achieve rather than the required amount. The more water used, the more transparent the underglaze looks. Thicker underglaze has greater intensity. 

Step #3: Apply Mixed Underglaze to a Test Piece

With untried underglazes, you may want to apply them to a test piece before putting them on the nice piece of pottery you created. The underglaze may react differently than what you expect. A test piece shows you how the underglaze will look when finished to not waste your efforts on an entire pot.

Unlike paints, underglazes do look different once fired in the kiln. They may darken or intensify, but the colors do look reasonably close. If you plan to use glaze, you can apply the glaze on top of the underglaze to see if you like how it looks.

Be aware: Clear Glazes that contain Zinc will change the underglaze color in some underglazes. In some cases drastically. That’s why test firing is so important. You don’t want to ruin what you have spent so much time creating.

When you mix underglaze colors, the test results may look fantastic in some cases, they may not look as good in other cases. My friend was mixing her underglazes and didn’t test fire. The colors did not turn out the way she wanted them to. That is one of the reasons why you want to fire a low-risk test piece any time you mix underglazes to learn what it looks like.

Step #4: Apply Underglaze to Your Pottery

Once you’ve mixed and tested the underglaze, time to choose your brush. Detail Brushes are great for applying underglazes. You usually want to apply two coats of underglaze. One coat may form streaks which are fine if that is your desired effect. Some potters apply as many as four coats. That, however, is unnecessary unless you want greater intensity, but the underglaze may crack or bubble the clear glaze if applied too thick.

While many potters apply underglaze with a brush. There are other ways to apply underglazes, including Sponging, Spraying, Bubble glazing, or even Dipping.

The great part about underglaze is you can apply it to bisque ware or greenware clay.

Applying to Greenware

Greenware clay refers to unfired clay pottery. Among the 7 Stages of Clay, you can apply underglaze to 3 different stages in the greenware state. Still, it’s usually best to at least let the clay reach a leather consistency. But this again goes with the effect you want to create.

Another good time to apply underglaze is when the clay is bone dry, but you must be very careful because it is in its most fragile state. Brushing the underglaze on greenware offers the advantage of letting you see a near-finished design. You can figure out the weak points and where to apply more underglaze after it’s been bisque fired. The second chance is another popular reason to apply underglaze on greenware.

Applying to Bisqueware

You also have a couple of advantages of applying underglaze on bisqueware.

Once bisque fired, the clay is now ceramic and no longer in a fragile state. Underglaze applied to bisqueware gives you a more accurate design with what the finished result will look like. 

After you applied the underglaze to your bisqueware, you will want to apply the Clear glaze. It’s important to allow the underglaze to dry thoroughly and be careful when brushing on your glaze. You don’t want to apply too much pressure to the brush, as the underglaze can smudge easily when applying the glaze to it.

Once the glaze is dry, it’s ready to put into the kiln for the final fire. I have applied underglaze on both greenware and bisqueware. I do favor applying it on bisqueware. That’s the great part about pottery, you can try the different stages of clay and choose the one that’s right for you.

Conclusion

Mixing Underglazes to create new color combinations for your pottery is so much fun to do. It’s a really cool way of expressing yourself and your creativity because you can create whatever colors you want!

However, it may not always work out the first time around. Sometimes it works great with one color, but it goes all wrong once another color is added. That’s why before applying it to your work of art, it’s important to test out any potential blends on a small sample first and make sure the colors are right for you. Happy Glazing!