Can You Make Clay From Dirt?

What is Clay?

Clay is a fine-grained natural soil material containing clay minerals like kaolinite, montmorillonite-smectite group, and illite among others (1). The clay minerals form through prolonged chemical weathering of other silicate minerals in soil or sedimentary rocks. Clay develops plasticity when wet, but can be hardened when heated through firing, which causes the clay minerals to bond more tightly (1).

The essential components of clay are silica, alumina, and water, but it also includes various amounts of iron, magnesium, alkalies, and alkaline earths (2). The properties of clay depend on the amounts and combination of these components. Common properties of clay include plasticity, shrinkage under firing, fineness of grain, and colloidal size of the mineral particles (2). When moist, clay becomes sticky and malleable, and can be shaped. When fired at high temperatures, the clay hardens permanently.

Clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, lack the plasticity and hardening behavior of clay when wet and fired.

(1) https://en.wikipedia.org/wiki/Clay

(2) https://www.britannica.com/science/clay-mineral

Clay vs Dirt

Clay is different from regular dirt or soil in a few key ways. Clay contains a high percentage of clay minerals, which give it its unique properties. Dirt and soil contain a mixture of sand, silt, clay, and organic matter. The percentage of clay minerals in clay can range from 20-40%, while regular soil contains less than 20% clay minerals (1).

The clay minerals in clay are very small, flat plate-like particles that stack together to form dense, cohesive masses. This gives clay its smooth, dense, and pliable characteristics that make it ideal for pottery and sculpture. Regular dirt has a mix of larger particles like sand and silt that make it less cohesive. Clay can be rolled, stretched, molded, and shaped, while dirt crumbles easily (1).

When wet, the clay minerals in clay absorb water molecules and expand. The absorbed water acts as a lubricant between the clay particles allowing them to slide over one another and be molded. As clay dries, the water evaporates away and the clay minerals bond tightly together through cohesive forces, giving clay its hardness and strength (1).

Clay also forms an impermeable, water-tight barrier when compacted. This is due to the flat clay particles stacking together without large pores for water to pass through. Soil and dirt are more porous from larger particles like sand, allowing water to drain through. So in summary, the abundance of clay minerals give clay its unique binding, molding, and water resistance properties compared to regular dirt (1).

(1) https://www.differencebetween.com/what-is-the-difference-between-soil-and-clay/

Making Clay from Dirt

To make clay from dirt, you first need to identify and collect clay-rich soil. According to the article on How to Process Soil into Clay for Pottery from https://practicalselfreliance.com/making-clay/, clay soil feels slick or sticky when wet and forms into a ball that can be rolled into a “snake” that holds its shape.

Once you’ve identified clay soil, you can extract the clay using the wet extraction method. Fill a bucket about 1/3 full with the soil, then add water and mix. Allow the clay to settle, then pour off the water. Repeat this process until the water pours off clear.

After extracting the clay, the next step is to screen and process it. Pour the clay slurry through a screen to filter out rocks, roots, and other debris. Allow the clay to dry partially, then break up any clumps and screen it again through a finer mesh. Knead the clay with your hands to achieve an even consistency.

Proper processing and screening ensures your homemade clay has a smooth, lump-free texture suitable for crafting and sculpting. Allow the clay to dry completely before using it in projects or storing it.

Test Clay Quality

Testing the quality of homemade clay is important to understand its properties and best uses. Some key tests include:

Plasticity – This measures how easily the clay can be shaped without cracking. Roll a piece into a coil. The clay should bend without breaking to be considered plastic enough for most uses like pottery or sculpture. Sticky or brittle clay has poor plasticity.¹

Stickiness – Excessive stickiness makes clay difficult to work with. To test, press a piece of clay between your fingers and slowly pull them apart. There should be some resistance but they shouldn’t stick together. Adding non-stick agents like talc can help reduce stickiness.

Cracking – Cracking can happen as clay dries if it has too much water or poor plasticity. Test by forming a slab and letting it dry slightly. Cracking means the clay needs modifications to improve plasticity before major projects.²

Firing – Fire a small dry piece of clay according to the planned firing temperature. Check for warping, cracking, or bubbling which indicates issues. The color change shows the clay’s fired hues.

¹ https://ceramicartsnetwork.org/daily/article/Testing-1-2-3-How-to-Test-Clay-Bodies-to-Find-the-Right-Sculpture-or-Pottery-Clay-for-Your-Work

² https://digitalfire.com/article/how+to+find+and+test+your+own+native+clays

Clay Recipes

One of the keys to making clay from soil is getting the right balance of clay particles with sand and organic matter. Here are some common recipes for making homemade clay using native soil:

A basic clay and sand mixture uses 2 parts clay soil to 1 part sand. The sand helps open up the clay so it’s more workable. Make sure to use a fine builders sand rather than course sand for the best results. Mix the ingredients together well in a bucket or wheelbarrow using a shovel or your hands.

To make clay with organic matter that fires at lower temperatures, use 3 parts clay soil, 1 part sand, and 1 part organic material such as sawdust, straw, leaves, or decomposed plant matter. The organic material burns out during firing, creating pores in the finished clay.

For earthenware or terra cotta clays, mix 3 parts red clay soil, 1 part sand, and 1 part organic matter. Allow the clay to soak in water for 1-2 days then knead thoroughly until smooth. The higher iron oxide content in red clay means it can be fired at lower temperatures around 1900°F.

To cite the source per the instructions: https://www.wikihow.com/Make-Clay-from-Indigenous-Soil

Clay Storage

Properly storing clay is crucial for keeping it workable and preventing mold growth. When storing clay long-term, the goal is to keep it moist and sealed away from air exposure.

Clay dries out quickly when exposed to air. To prevent this, store clay in airtight plastic bags or containers. Wrap clay in plastic wrap or bag it before placing in an airtight plastic bin with a tight fitting lid (Seattle Pottery Supply). The plastic wrap or bag creates a moisture barrier while the bin prevents air exposure.

For very long term storage, some clayers recommend freezing clay. Freezing prevents mold growth and keeps clay indefinitely workable. Let frozen clay thaw completely before using again (Bailey Pottery).

Check stored clay periodically for moisture level. If exposed to air, clay can dry out. Re-wrap or re-bag clay as needed to maintain a moisture barrier. With proper storage methods, clay can remain usable for months or years.

Projects with Homemade Clay

Homemade clay can be used for a variety of fun and creative projects. Both fired and non-fired clay items can be made at home.

For non-fired clay crafts, air-dry clays are a good option. These clays harden through evaporation without needing to be kiln-fired. Some ideas for air-dry clay projects include:^{1, 2}

• Jewelry and beads
• Figurines and sculptures
• Bowls, vases, and pots
• Magnets, coasters, and wall decor
• Ornaments, candles, and decorative objects

For items that require firing, homemade modeling clays made from natural materials like clay soil, flour, and water can be used. Firing hardens and strengthens these clays. Projects might include:²

• Mugs, dishes, and tableware
• Tiles and garden decor
• Sculptures and pottery

The type of homemade clay and project will determine the required firing temperature and technique. But with the right clay recipe and firing method, homemade clays can produce items as durable as professionally made pottery.

Pros and Cons of Making Your Own Clay

There are several benefits as well as drawbacks to consider when making your own clay from dirt. Some of the main pros include:

• Cost Savings – Making your own clay is much cheaper than purchasing pre-made clay, especially for large projects.
• Customization – You can experiment with different dirt sources and recipes to achieve the exact clay consistency, texture, and color you want.
• Sustainable – Repurposing dirt into clay reduces waste and relies on ingredients you likely already have at home.

However, there are also some potential cons to keep in mind:

• Labor Intensive – Processing dirt into smooth, workable clay involves extensive labor including drying, breaking up clumps, sifting, and kneading.
• Quality Control – Homemade clay can develop cracks or breakage if the composition and firing process are not calibrated properly.
• Limited Selection – You may not be able to achieve the diverse colors and sculpting properties possible with manufactured clay.

Testing small batches first and following clay recipes closely can help maximize the pros and avoid the cons when opting to make your own clay at home.

Sources: https://www.provenwinners.com/learn/dirt-dirt-clay, https://www.masterclass.com/articles/clay-soil

Purchasing Clay

There are many options when it comes to purchasing clay. Brick-and-mortar craft stores such as Michaels and Hobby Lobby carry a variety of clays that are convenient to buy if you need it right away. Online retailers like Amazon and The Ceramic Shop offer even more choices at competitive prices, especially when buying clay in bulk.

For beginners, an air-dry clay that doesn’t require firing is a good place to start. These clays are easy to work with and dry at room temperature. However, pieces made from air-dry clay are more fragile.

For more advanced projects, pottery clay that must be fired in a kiln is preferred. The most common types are stoneware and earthenware. Stoneware is very strong and durable after firing. It has a smooth, non-porous surface. Earthenware is more porous but can achieve bright glazes. Consider the type of projects you want to create when deciding which clay to purchase.

Buying clay in bulk online can save money compared to buying small amounts at local stores. Purchasing 25-50 lbs at once results in the lowest price per pound. If properly stored, pottery clay lasts for years. For large quantities, check with local pottery studios – they may sell directly to the public at wholesale prices.

Tools for Working with Clay

When working with clay by hand, whether sculpting or handbuilding, there are some basic tools that are essential:

Potter’s needle – This is a long, thin metal tool used for scoring and cutting clay as well as smoothing seams between pieces of clay. It has a sharp point on one end and a knob on the other end for grip (Source 1).

Loop tool – This metal tool has a rounded, smooth tip used for smoothing clay surfaces and burnishing. It comes in various sizes for both detailed and larger smoothing work (Source 2).

Fettling knife – This is a small knife with a straight blade used for trimming excess clay from pieces and cutting and scraping clay. The blade can be curved or straight (Source 1).

Ribs – These are stiff, blunt metal or wooden tools used for smoothing, burnishing, and shaping clay. They have rounded edges and come in various widths (Source 1).

Cutting wire – This thin wire is used to cut slabs and blocks of clay. It easily slices through clay with pressure (Source 1).

Sponges – Sponges are helpful for smoothing, texturing, or adding water to clay surfaces (Source 1).

With just these basic, affordable tools, clay can easily be sculpted, smoothed, shaped, cut, scraped, and joined to create an endless variety of forms and ceramic pieces.