What Clay Can You Make Cups Out Of?
Clay is one of the most versatile and ancient materials used by humans to make objects like pottery, ceramics, and sculptures. The history of working with clay dates back over 25,000 years to when prehistoric peoples started crafting simple clay figurines and vessels. Ever since these early beginnings, clay has captivated artists and makers because of its malleability, abundance, and ability to be transformed through heat. When clay is fired in a kiln, it undergoes a chemical and physical change that permanently hardens it. This process allows humble lumps of clay to be shaped into stunning works of art, dinnerware, tiles, and more.
Making pottery and ceramics from clay remains a popular craft today, in part because it is an accessible and forgiving medium. With a basic understanding of the different types of clay, sourcing, preparation techniques, shaping methods, and firing, anyone can work with clay to produce beautiful and functional creations. This guide will provide an overview of working with clay and how to make cups, one of the most common and useful pottery forms.
Types of Clay
There are three main types of clay that are commonly used for making pottery such as cups:
Earthenware
Earthenware is a porous clay that is fired at lower temperatures, typically between 1,800-2,200°F. It can be left unglazed or finished with a glaze. Earthenware is very workable and flexible. It’s also affordable and accessible. However, it has lower durability and strength compared to other clays. Some common types of earthenware clay are red art clay, terracotta, and white earthenware.
Stoneware
Stoneware is dense, impermeable clay that is fired around 2,200-2,400°F. The higher firing temperature makes it more durable and watertight compared to earthenware. It comes in various colors including buff, grey, and brown. Some types of stoneware clay include porcelain stoneware and ball clay.
Porcelain
Porcelain clay is very pure, white, and translucent. It is fired between 2,400-2,550°F, resulting in a vitreous and non-porous ceramic. Porcelain is highly resistant to chipping and staining, but the high firing temperature means it requires more skill and experience to work with. Some types of porcelain clay are bone china, Imperial porcelain, and limoges porcelain.
Properties of Clay
Clay has several key properties that make it ideal for molding into cups and other ceramic objects.
Plasticity refers to clay’s ability to be shaped and molded without cracking or crumbling. Good plasticity means the clay can be pushed, pulled, rolled, and formed into your desired shape. Plasticity occurs because the tiny platelet particles in clay slide over one another when pressure is applied.
Porosity refers to the tiny pores within clay’s structure. These pores allow water to permeate into the clay. As the clay dries, the water evaporates out of the pores. The more porous the clay, the more water it will absorb.
Shrinkage occurs as the clay loses moisture during the drying and firing process. The clay particles move closer together as the water evaporates, causing the clay to shrink. Less porous clays will shrink more. Shrinkage must be accounted for when making ceramics.
absorbency refers to a clay’s ability to absorb water. More absorbent clays with higher porosity will absorb more water, resulting in more shrinkage when dried. Less porous clays absorb less water.
Plastic clays with good plasticity, porosity and absorbency are easiest to form into cups without cracking and deforming. Knowing the properties helps select the right clay for cup making.
Sourcing Clay
Most places that sell arts and crafts supplies will carry at least one or two kinds of pottery clay. Local craft stores like Michael’s, Joann Fabrics, and Hobby Lobby all typically sell potter’s clay in natural colors like gray, brown, red, and white. These clays may be sold as either moist clay that is ready to use, or dry clay that requires soaking in water for several hours or overnight before using.
A better option is to visit a ceramic supply store, where you will find an extensive selection of prepared clays for throwing on the wheel, handbuilding, sculpting, and more. These specialized stores often carry clay in 25 lb or 50 lb bags and a wide variety of colors and firing temperatures beyond what you’ll find in craft stores. Staff at a ceramic supply store can provide guidance on the best clay bodies and firing temperatures for your desired projects.
If you want to work with natural, unprocessed clay you’ll need to source it locally from deposits in the ground. Be sure to obtain permission before digging up any clay, and research local geology to identify clay deposits. Natural clay will need extensive wedging and processing to remove rocks, dirt, and debris before it can be worked. The composition and firing range will also be uncertain without testing. While challenging, working with raw natural clay can let you create pieces reflecting the local materials in your area.
Wedging Clay
Wedging clay is an important step before using it to make pottery or cups. Wedging involves kneading the clay to prepare it for throwing, handbuilding, or sculpting. There are a few key reasons why wedging is so important:
Wedging removes air bubbles – Air bubbles trapped in clay can cause cracks and explosions in fired pieces. The kneading action of wedging forces out any air pockets.
It homogenizes the clay – Wedging blends clays with different moisture levels and makes the texture more uniform throughout the clay body.
It conditions the clay – The repetitive action of cutting, folding, and pressing softens stiff clay and firms up moist clay. Well-wedged clay has the perfect plasticity for working.
To properly wedge clay, cut off a workable chunk from your clay. Repeatedly cut the clay in half, fold it over on itself, then press down with the heels of your hands. Turn the clay quarter turns as you go to evenly wedge in all directions. About 5-10 minutes of wedging by hand should prepare your clay. Avoid over-wedging, which can make the clay tired. The clay is ready when it has an even, smooth, workable texture throughout.
Shaping Methods
There are many techniques that can be used to shape clay into cups, bowls, plates, and other vessels. The main methods include:
Pinching
Pinching is one of the most basic and ancient clay shaping techniques. It involves pressing, pinching, and pulling the clay with your fingers and thumbs to form pottery. Pinch pots are made by pinching clay into an open bowl or vase shape. This method can be used to make simple cup forms.
Coiling
The coiling technique involves rolling out “snakes” or coils of clay and stacking them on top of each other in a spiral pattern. The coils are blended together using fingers or a tool to bond them. Coiling enables building taller vessels and unique asymmetrical forms. It’s possible to build cups coil-by-coil.
Slab Building
Slab building involves rolling out flat “slabs” of clay and cutting shapes that are assembled into the desired form. Cups can be made by cutting a curved slab for the outer wall and a circular slab for the base. The seams are blended to bond the slabs. Slab building allows for asymmetrical forms.
Wheel Throwing
The potter’s wheel enables throwing symmetrical rounded shapes like cylinders, bowls, and cups. Clay is centered on the wheel and opened up by pushing thumbs into the center. Using the hands and tools, the rotating clay is shaped into the desired cup form with walls of consistent thickness.
Drying & Firing
Allowing clay to dry properly before firing is a crucial step in the ceramic process. As clay dries, the water evaporates, making the clay denser and more stable. Here are some tips for properly drying clay:
- Allow clay to dry slowly, do not rush the process. Drying too quickly can cause cracks as the clay shrinks.
- Let clay air dry indoors out of direct sunlight. Direct sun causes uneven drying.
- Control humidity when drying clay indoors. Too much moisture in the air slows drying.
- Wrap clay in plastic if it is drying too fast. This retains moisture and prevents cracking.
- Use a kiln to fully dry clay if natural air drying is not possible.
Once clay is fully dry, the next step is firing in a kiln. Firing brings clay to it’s mature state, ending the drying process through intense heat. The keys to proper kiln firing are:
- Follow the temperature guidelines for the type of clay used. Firing too hot can melt clay.
- Use slow, gradual temperature increases over many hours.
- Allow proper ventilation in the kiln for oxidation. This reduces dark colors on the clay.
- Fully fire clay pieces to cone temperatures for hardness and durability.
With proper drying and firing techniques, clay is transformed into a hardened and durable ceramic material perfect for use in cups, bowls, and other vessels.
Glazing
Glazing is an important step in creating usable and beautiful ceramic pieces. Glazes serve several purposes in the ceramic process. First, glazes make pieces impermeable, preventing absorption of liquids into the porous clay body. Glazes also add an decorative element, with colors, textures, and effects. Finally, glazes strengthen the finished ceramic by adding a glassy coating that is durable and resistant to scratching.
There are many techniques for applying glazes. The most common methods are dipping pieces into liquid glazes, pouring glazes over pieces, and spraying glazes with a spray gun or airbrush. Some effects like dripping or banding require special application techniques. Glazes can also be painted on with brushes for detailed decorative work.
Glazes come in various types. Common categories include transparent, opaque, satin, matte, crystalline, and high-fire glazes. Within these types many colors are possible from metallic lustres to vibrant primary colors. Choosing the right glaze for the clay body, desired look, and firing temperature takes some experimentation to achieve optimal results.
Making Cups
When making cups out of clay, there are several design considerations to keep in mind.
The rim of the cup should be smooth and even. An uneven rim can cause spilling and make the cup unpleasant to drink from. Use your fingers or a rib tool to smooth the rim after shaping the cup.
Decide whether to add a handle or not. Handles provide grip but can also break off in the firing process if not attached securely. Use slip to firmly attach handles and score the surface where the handle meets the cup body.
Consider etched or impressed designs. You can etch patterns into leather-hard clay using tools. Or press objects like leaves or lace into the surface to leave behind impressions. Just take care not to make the cup walls too thin.
Allow adequate drying time before firing, especially for larger or thicker-walled cups. Dry cups slowly and evenly to prevent cracking and warping. Once bisque fired, smooth any rough areas with fine sandpaper before glazing.
Apply glaze carefully inside the cup if it will hold liquids. Use a consistent glaze thickness and avoid drips. Leave the foot or base unglazed if the cup will sit on a surface. Finally, fire a second time according to the glaze instructions.
Conclusion
Cups are one of the most common yet beloved ceramic items. Choosing the right clay is essential to making durable and beautiful finished cups. Red and white firing clays like stoneware and porcelain are ideal choices due to their strength, workability and aesthetics.
Kneading the clay properly ensures an even distribution of moisture and removes air pockets that could lead to cracking. Once wedged, the clay can be shaped into a cup form through methods like wheel throwing, handbuilding or slipcasting. Careful drying and firing will complete the ceramic process.
The finished cups can then be left plain, painted, stained or glazed for decorative effects. A final firing will make the glaze permanent. With the right clay and techniques, ceramic artists can craft an endless variety of stylish, functional cups to be enjoyed for years to come.
In summary, clay selection, preparation, shaping, drying, firing and finishing are the key steps in creating high quality ceramic cups. With practice and an understanding of the process, both professional potters and hobbyists can successfully make their own beautiful, homemade cups.
