Most people buy their clay at the store, but it is essentially dirt. In fact, many of us probably walk past usable clay on our way to buy clay.

In this video, I discuss three ways to make your own clay at home using dirt. I also explain when each method is best used.

What is clay?

If you look up a technical definition of clay, it is a sediment with particles smaller than silt. That definition helps us understand that not all dirt will work the same way for making clay. Some dirt contains a lot of clay, while other dirt contains almost no clay. This is why some “make clay from dirt” videos show people struggling to get usable clay.

For example, in some popular videos, someone may start with a bucket of dirt and end up with only a handful of clay. That usually means the dirt they collected did not contain much clay.

How to recognise clay-rich dirt

Dirt that contains a lot of clay often has recognisable properties.

When wet, clay-rich dirt may feel sticky or plastic, meaning it holds together and can be shaped. When dry, you may see clues such as:

• Tire tracks that stay visible for a long time, because clay helps hold the shape.

• A crackled surface texture, showing that the clay expands when wet and contracts when dry.

A crackled texture often suggests a higher percentage of clay.

Today I will collect dirt from three different locations around town. Then I will take the samples back to my studio and test them to see how much clay they contain. This will help us decide which processing method each sample needs.

Testing three dirt samples

I have three samples of dirt from different places around town. Now I need to determine how much clay and how many impurities each sample contains.

First, I grind each sample into a loose powder using my hands. Then I add water.

Once the dirt is wet, I can feel how clay-like it is: how well it sticks to itself, how plastic it feels, and how gritty it is. This helps me decide how much processing is required.

Sample 1

Sample 1 is high in clay. It sticks to itself well and feels plastic. Because I collected it from an area with traffic, it contains some plant bits and gravel. I will screen it to remove larger debris, but I do not think it needs heavy purification.

Sample 2

Sample 2 feels like a fairly pure clay. It has a good texture and does not contain noticeable plant material or rocks. This sample does not need much purification, so I will dry-process it.

Sample 3

Sample 3 is gritty and contains gravel and sand, and likely silt as well. It does not hold together well. This sample needs significant purification, so I will use levigation to separate the clay from the sand and silt.

Method 1: Screening (Sample 1)

For sample 1, I begin by screening.

I put the dirt into a bucket, add water, and mix it until it is thin and smooth with no lumps. Then I pour the mixture through a screen.

You can use a purpose-made strainer screen, but you do not need special equipment. A piece of window screen or a section of screen mesh from a hardware store can work.

After screening, I now have liquid clay. Next, I need to remove excess water.

I let it sit for about an hour so the clay settles to the bottom. Then I pour off the clear water from the top.

The clay is still too wet to use, so I pour it into an old pillowcase. I set the pillowcase outside so the water can drain and evaporate until the clay reaches a workable consistency.

Method 2: Dry processing (Sample 2)

For sample 2, I use dry processing. This is the fastest method when your dirt is already close to pure clay.

I crush the dry clay into powder using a rock on a hard surface. Clay usually breaks down easily and does not need to become perfectly fine like flour.

If your clay is too wet to grind, you can leave it in a covered area for a couple of weeks so it dries out.

Method 3: Levigation (Sample 3)

For sample 3, I use levigation. Levigation uses gravity to separate particles by size.

I add water, mix the dirt thoroughly, and break up any lumps. Then I let it sit briefly—about one or two minutes.

The larger particles, such as sand and silt, settle quickly to the bottom. The clay stays suspended longer. I pour off the clay-rich liquid into a second bucket.

I repeat this process several times: add water, mix, let settle briefly, and pour off the liquid clay. I continue until the first bucket contains mostly grit.

Now the second bucket contains mostly liquid clay. I let it sit longer so the clay settles to the bottom. This may take an hour, or you can leave it overnight. Then I pour off the clear water at the top.

The remaining clay is still too wet to use. To dry it, I pour it into a cotton cloth trough supported by bricks. Moisture drains through the cloth and evaporates from the top. By the end of the day, it should become workable.

Adding temper (important final step)

Even after making clay, there is another important step before using it for pottery.

All clay shrinks as it dries. If it dries unevenly, it can crack. To help reduce cracking and improve thermal shock resistance, temper is added.

Temper is any non-plastic material mixed into clay. The clay itself is plastic and mouldable. Temper provides structure and reduces shrinkage stress.

In commercial clay, temper is often grog, which is fired clay that has been crushed into a granular material. In wild clay, temper can be grog, sand, volcanic ash, or diatomaceous earth.

A useful general guideline is to add about 20% non-plastic material.

I collected sand and will add about 20% to these clay bodies.

I have not mixed the dry-processed clay yet because it is easier to add temper while the clay is dry. When clay is wet, measuring and mixing temper evenly is more difficult and requires extended kneading.

Now that you know how to make clay from dirt, you may want to learn how to find clay in nature near your home. I have another video on that topic.

Thanks for watching. I will see you next time.