Stages of Clay 101

Some of the oldest pieces of pottery pre-date agriculture and human settlements. More than 20 millennia have passed, yet it seems that the way we play with clays hasn’t changed at all.

Here are the 7 stages of clay and the journey humble dry powder goes on to become an amazing work of art.

1 – Dry Clay

putting water in dry clay

The skinny: Powder or dry chunks. Add water to continue.

The first stage is how you get to meet your clay for the first time. It’s a dry powder that contains titanium, kaolinite, mica, quartz, and other minerals. You’ll most likely work with Ball Clay when making pottery, but you may also encounter other types like the Kaolin China Clay, Red Clay, etc.

clay chunk ready to mold

Dry clay has all of its moisture removed, making it easier to ship and store. As the matter of fact, you can store dry clay forever as long as you protect it from moisture.

You can also make dry clay from scraps (from previous projects) or even dig some up (depending on where you live). As long as it doesn’t go through the final stages, all you have to do is to let it dry completely, and smash it into a powder with a hammer.

2 – The Slip Stage

wet clay

The skinny: Suitable for molds, gluing pieces together and decorating.

To get into the slip stage, all you have to do is add water to dry clay. The consistency is slightly softer and runner than the plastic stage, resembling royal icing.

Just like the royal icing, you can use the clay to “write” all over your project. This will result in added texture and/or 3D decorations. The clay is also pourable and runny enough for silicone or a wax mold.

This stage of clay is also suitable for gluing handles and other elements to your project, or patching cracks and mistakes as you work. Always keep at least a small amount at your side while working on your project.

It takes time to learn how to get the right consistency. It can’t be too hard or too wet. You can keep it fresh by adding a splash of vinegar when mixing.

3 – The Plastic aka Workable Stage

lump of clay in hands
Potter holds lump of clay in hands. Front view on potters hands holding lump of clay. Process of working with clay.

The skinny: Time to build your project.

This is what most people imagine when they think of wet clay. It’s the stuff that’s sitting on your working surface or the pottery wheel, waiting to become a vase, bowl, or another project. At this stage, you can shape the clay any way you wish, and you’re (almost) a step away from firing the project in the kiln.

Though, there is a right consistency for this stage as well. Too dry and it will crack, too wet and it will flop. The type of clay you’re using and your environment will determine the sweet spot, and you’ll figure out where it is by getting your hands dirty.

4 – The Leather Hard Stage

putting handle on pottery
Professional male potter working in workshop, studio – putting handle on ceramic jar.

The skinny: Clay is dry enough for trimming and adding handles, but not fully hardened.

At this stage, clay feels like soft leather. It’s not dry by any means, but it doesn’t feel fully wet to the touch. You know you’re there when you touch your projects and don’t leave your fingerprints behind.

Now the project is ready for trimming and getting those edges perfected. You can also add handles or decorations with the slip stage clay as well.

However, there’s a chance that you left the clay to dry for a bit too long. You can still give the project a few polishing touches with he sandpaper or smooth the surface with a wet sponge.

If you’re not sure if you can get to your project in time, wrap it in some plastic. A simple grocery bag will do, and it will buy you at least a week before you can get back to it.

5 – The Bone Dry Stage

Potter preparing ceramic wares for burning
Professional male potter preparing ceramic wares for burning in pottery kiln with milk – old russian pottery tradition. Crafting, artwork and handmade concept

The skinny: The clay is dry, ready for the kiln.

About a week or so (this depends on the moisture levels in your environment) after the leather hard stage, the clay will be dry enough to go into a kiln. It’s super important that the clay dries out before firing. That is unless you want it to explode in the kiln – to each their own, I guess.

A good rule of thumb is to see if your project looks fully dry, and then give it a few extra days. You’re looking for the light, as in lighter color and lighter weight (both caused by water evaporation). It will also be crumbly, so you can use scraps and create test pieces.

Those test pieces (and unsuccessful projects) can now be smashed and recycled into dry clay as well.

6 – The Bisque/Bisqueware Stage

male potter examining jug
Professional male potter examining earthenware jug in pottery workshop, studio.

The :skinny: The project had its time in the kiln, ready for a glaze.

The first firing of your project. The heat removes all remaining water and impurities, and it leaves a smooth yet porous surface. You can apply an underglaze at this stage as well (or do final touch-ups if you applied the underglaze during the leather hard stage).

And we are really cranking up the heat – anything between 1728 (Cone 8) and 1945 degrees Fahrenheit (Cone 4). So, if you’re lucky enough to have a kiln at home, practice precaution.

This stage can last up to 3 days from start to finish. After this point, the clay can’t be recycled and turned into a dry powder stage anymore.

You can leave the pottery unglazed or smoosh these last two steps with a technique called raw-glazing.

7 – The Glaze Firing Stage

Female potter hands polishing clay pot
Close up of woman ceramic artist using grinding block while polishing earthenware vase

The skinny: The final step – seal and polish.

Once you have the bisque pottery, it has to go through a bit of prep. It mostly consists of wiping them down with a damp sponge to remove fingerprints and dirt, then leaving them to dry again. Then, it’s time to crank up the heat again.

There are so many glazes that you can choose from. However, you have to pay attention to the “baking” instructions. Both glazes and clays can be fired at different temperatures and it’s important to match them correctly so your project doesn’t melt in the kiln.

When you’re shopping for the supplies, they will be marked for low fire, mid-fire, or high fire. If they have numbers, the mid-fire materials will say they are for cone 5 or 6. Watch out for the zeros! If the package says 05 or 06, it’s a low fire. High fire suitable clay and glazes will say that they are suitable for cone 10.

Each glaze will come with complete instructions on how to apply it and “bake” correctly. Once the project goes to into the kiln for the final time, you will be able to hold the fruits of your labor in your hand in 12 to 24 hours.