If you are just starting out in ceramics, you may have heard about the ‘density’ of glazes. But what exactly does this mean? The density of a glaze refers to how thick or thin the glaze mix is. In simple terms, it is the ratio between the amount of glaze ingredients and water in your mix. So, if you prepare your glazes from a powder mix, you need to take this into account to get good glazing results.
Why is the right density important?
The right density of your glaze is crucial for several reasons. It determines the thickness of the glaze layer on your work, how well the glaze adheres to the clay, and it can affect how the glaze melts and flows during firing. So you’ll understand that it can greatly affect the final result of your work.
How do you measure the density of a glaze?
With a density meter, or densimeter:
First of all, it is important not to measure until your prepared glaze has been resting for at least 24 hours. The ingredients in the mix absorb water. This takes time, and can affect the density.
There are several ways to measure the density of your glaze, but one of the most common methods is with a density meter, also called a hydrometer. You can buy such a density meter at the pottery supply store.
Here’s how to proceed:
- Mix your glaze really well
- Fill a tall cylinder or measuring cup with your glaze
- Carefully lower the density meter into the glaze
- Wait for the meter to stabilize and read the value where the liquid surface crosses the scale
Most ceramic glazes have a density between 1.45 and 1.65 grams per milliliter. But the ideal number can vary depending on your specific glaze and application.
Without density meter:
Even if you don’t have a density meter (yet), you can still measure the density.
Our teacher Caroline from the course Preparing and understanding glazes does it this way:
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- Mix your glaze really well
- The density of water = 1
The density of glaze is more than 1, the ingredients are ‘heavier’ - Put a measuring cup on your scale and set to ‘0’
- Pour 1 liter of glaze into your measuring cup
- What is the weight? Between 1,450 and 1,650 grams is right.
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Tips for adjusting density
Is your glaze too thick or too thin? No worries, you can adjust the density:
- Glaze too thick? Carefully add small amounts of water; mix well and measure again.
- Glaze too thin? Let the glaze rest for a day, then pour off some water. Measure again and adjust until the density is right.
Remember: it is always better to adjust in small steps and test regularly!
Understanding and controlling the density of your glaze is an important skill for any ceramicist. With some practice and patience, you will find that you gain more control over your glaze results. Experiment, take notes and most importantly, enjoy the process!
