Can I Make My Own Porcelain?

What is Porcelain?

Porcelain is a ceramic material made by heating raw materials like clay, feldspar, and quartz to high temperatures. It is known for its whiteness, strength, translucency and resistance to chemical attack. Porcelain has a very low porosity, meaning it is impermeable to water.

The word “porcelain” comes from the old Italian word “porcellana” meaning cowrie shell, due to its resemblance to the surface of polished shells. Porcelain originated in China during the Tang Dynasty (618-906 AD) and became known as “china” in English.

Porcelain is made from kaolin clay, which gives it plasticity and strength when fired. Feldspar and quartz give it durability and resistance to thermal shock. Additional ingredients like bone ash can be added to increase whiteness. The raw materials must be finely ground and mixed in the correct proportions.

Key properties of porcelain include its whiteness, hardness, low porosity, high strength, translucency, resonance, and high resistance to chemical attack and thermal shock. This makes it ideal for products like tableware, sanitary ware, electrical insulators, dental prosthetics, and decorative art objects.

Porcelain is widely used to make dishes, mugs, vases, figurines, handles and knobs, tiles, and other decorative and functional objects for residential and commercial use. Its durability, hygienic properties, and aesthetic qualities make it a versatile ceramic material.

Porcelain vs Ceramic

Porcelain and ceramic are both inorganic, non-metallic solids made from firing clay or other raw materials. However, there are some key differences between the two:

Composition – Porcelain contains kaolin clay and feldspar, resulting in a white, translucent appearance when fired. Ceramic can contain any clay body. The clay composition affects the color and properties.

Firing Temperature – Porcelain is fired at extremely high temperatures ranging from 2,300°F to 2,500°F. Ceramic is fired at lower temperatures from 1,800°F to 2,200°F.

Density and Strength – Porcelain is highly vitrified and non-porous, making it stronger, harder and less permeable than standard ceramic. Porcelain has high flexural strength.

Porosity – Porcelain has almost zero porosity whereas ceramic often maintains some slight porosity after firing. This makes porcelain more durable and water/stain resistant.

Uses – Due to its durability and aesthetic qualities, porcelain is often used for items like dinnerware, sanitaryware, electrical/building insulators. Ceramic has wider uses including floor and wall tiles, pottery, bricks, etc.

In summary, porcelain is a specific type of ceramic known for its white color, strength, translucency and resistance to liquid absorption. All porcelain is ceramic, but not all ceramic is porcelain.

Porcelain Clay Ingredients

Porcelain clay consists of three main ingredients: kaolin, feldspar, and quartz. Kaolin, also known as china clay, is the primary ingredient that gives porcelain its white color and plasticity when mixed with water. Feldspar acts as a flux, lowering the vitrifying temperature of porcelain. Quartz adds additional strength and structure to the final fired porcelain.

Kaolin is a white clay mineral that is found in deposits formed from the chemical weathering of aluminum silicate minerals like feldspar. It is composed primarily of kaolinite but also contains other clay minerals and mineral impurities. The best kaolin for porcelain has a high proportion of kaolinite, which results in white firing color and high plasticity when mixed with water.

Feldspar is an igneous rock mineral that melts at low temperatures relative to other minerals. It acts as a flux in porcelain, promoting vitrification at lower temperatures. Feldspar lowers the melting point of the silica in the clay body, allowing the porcelain to fully mature and become non-porous in the kiln at typical firing temperatures. The most common feldspars used are potassium and sodium feldspars.

Quartz is added to strengthen the porcelain clay body. Quartz grains remain intact through firing and act as a structural framework in the dense porcelain body. Quartz has a much higher melting point than feldspar, so it does not flux the body. The quartz partially fuses with the vitrified body, adding durability and hardness to the final porcelain product.

Tools and Supplies Needed

Making porcelain at home requires some basic supplies and equipment. The most important tools are:

• Kiln – A kiln capable of reaching over 1300°C is needed to fully vitrify porcelain and achieve translucent results. Look for a small hobbyist kiln or a secondhand one.
• Mold – Plaster molds are useful for repeatedly shaping porcelain into forms like cups, vases, bowls, etc. Molds can be bought or made from scratch.
• Clay tools – Basic tools like small spatulas, loop tools, ribs, cutting wires, etc. will help shape, smooth, trim, and refine the porcelain.
• Glazes – Special porcelain glazes are used to decorate and color the pieces after bisque firing. Both commercial and homemade glazes can be used.

Other helpful supplies are a pottery wheel, clay extruder, slip trailers, brushes, banding wheels, etc. Having the right studio setup makes porcelain creation much easier.

Shaping and Molding Porcelain

There are three main techniques for shaping and molding porcelain:

Wheel Throwing

Wheel throwing involves using a pottery wheel to throw and shape porcelain clay into forms and shapes. This takes practice to master, as you need to center the clay on the wheel and learn techniques for opening up the walls of the clay and raising it up into different forms. Wheel throwing allows you to create symmetrical round shapes and vessels.

Slip Casting

Slip casting involves pouring liquid porcelain slip into plaster molds. The porous plaster absorbs water from the slip, forming a layer of clay on the inside of the mold. Once the desired thickness is achieved, the excess slip is poured out of the mold. The porcelain takes the shape of the mold as it dries. Molds can be reused to create multiple cast pieces.

Handbuilding

Handbuilding involves shaping porcelain clay entirely by hand without the use of a wheel or mold. Techniques like pinching, coiling, and slab building allow you to create free-form sculptural pieces. This method provides the most creative freedom but requires strong modeling skills.

Drying and Firing

After you have shaped and molded your porcelain, it needs to thoroughly dry before firing. Porcelain clay contains water that must be fully evaporated before firing or else cracking can occur. Allow your porcelain pieces to air dry slowly at room temperature for at least 1-2 weeks. The drying time can vary based on factors like humidity, thickness of the clay, etc. Test the pieces by touching them to your cheek. If they feel cool, they are likely ready for firing. Avoid drying porcelain in direct sunlight or with heaters as this can dry the outer surface too quickly.

Once dried, the porcelain then needs to go through two firings – a bisque fire and a glaze fire. Bisque firing refers to the first firing of the dried unfired clay before any glazes are applied. This initial bisque firing further hardens the clay body through sintering and makes the structure more durable. Typical bisque firing temperatures are around 1800°F – 2100°F. When bisque firing porcelain at home, use a kiln and program it to slowly ramp up to the peak temperature. Allow sufficient soak time at the peak temperature before slowly cooling.

After the bisque fire, glazes can be applied to the porcelain for decorative effects and to create a non-porous surface. The glazed pieces are then fired again at an even higher temperature around 2300°F. This melts the glazes so they fuse with the bisque ware porcelain body beneath. Slow cooling is critical to prevent crazing of the glaze. Firing schedules and peak temperatures can vary slightly based on the specific clay body composition and glazes used.

Applying Glazes

Glazes are an essential part of finishing and decorating porcelain pieces. They serve both decorative and functional purposes by adding color, effects, and sealing the porous clay surface. There are many options when it comes to glaze ingredients and application methods.

Common glaze ingredients include silica, fluxes, alumina, colorants, and mixers. Silica provides the glassy coating, fluxes lower the melting point, alumina stiffens the glaze, colorants add color, and mixers improve application properties. These ingredients are combined based on glaze recipes to achieve the desired characteristics.

Glazes can be applied using a variety of techniques:

• Dipping – Fully submerging ware into a container of glaze
• Pouring – Carefully pouring glaze over the surface
• Brushing – Using a brush to apply glaze
• Spraying – Spraying glaze through an airbrush tool
• Sponging – Dabbing on glaze with a sponge

Proper glaze application involves ensuring full coverage, avoiding drips, and controlling thickness. Multiple coats may be used to build up layers. Test tiles are helpful when testing new glaze recipes and methods.

Tips and Tricks

Creating porcelain at home can be challenging, but with some helpful tips and tricks, you can avoid flaws and achieve beautiful results.

Avoid Air Bubbles

Air bubbles are one of the most common flaws found in homemade porcelain. To avoid them:

• Wedge your clay thoroughly before shaping to remove any air pockets
• Tap molds gently while pouring in slip to release trapped air
• Pour slip in one spot, avoiding pouring from high up
• Allow slip to sit for a while before firing so air bubbles can rise

Prevent Cracking and Warping

Cracking and warping can occur during the drying and firing process. To prevent this:

• Dry pieces slowly and evenly in a climate-controlled space
• Avoid drying pieces in direct sunlight or near heating sources
• Fire pieces slowly and increase kiln temperature gradually
• Allow sufficient hold times at crucial temperatures to allow heat to fully penetrate pieces
• Allow pieces to cool slowly and completely before removing from kiln

Achieve an Even Glaze

An uneven glaze can ruin an otherwise beautiful porcelain piece. For best results:

• Clean piece thoroughly and remove all dust before glazing
• Apply glaze in an even coat, avoiding drips
• Fire glazed pieces slowly and evenly according to glaze specifications
• Always test new glazes on test tiles first to observe results

Safety Considerations

Working with porcelain clay requires taking some safety precautions. Proper ventilation and safe handling of clay are important to avoid potential health hazards.

Clays contain silica dust which can be harmful if inhaled over long periods of time. When working with porcelain clay, use a ventilating system or open windows to circulate fresh air. Wear a protective face mask or respirator while sculpting, sanding, and cleaning up dried clay dust. Avoid touching your face when working to prevent ingesting clay particles.

When mixing clay, do so gently to minimize dust. Wet mop floors and wipe down countertops to remove dried clay residue. Clean tools in the sink to avoid splashing clay water. Store clay in a sealed container. Take measures like washing hands after handling clay and changing out of dusty clothes to prevent exposure.

Clay can be heavy and place strain on wrists, fingers, and shoulders during sculpting. Take breaks and avoid repetitive motion. Let clay adequately dry before lifting to prevent injury. Properly prepare clay to optimal consistency and keep tools sharp.

Follow all manufacturer safety guidelines. With appropriate ventilation, safe handling procedures, and general care, creating porcelain at home can be an enjoyable hobby.

Getting Started at Home

For beginners interested in making their own porcelain at home, the easiest way to start is with a complete porcelain making kit. These kits contain all the basic tools, materials, and instructions needed to make simple porcelain pieces. Look for kits that include porcelain clay, modeling tools, glazes, and safety equipment like gloves and masks.

Another option is to take a porcelain making class at a local ceramic studio or community college. Hands-on instruction from an expert is extremely valuable when learning any new art or craft. Classes allow you to use studio equipment and receive feedback on your techniques. Be sure to ask about beginner-friendly options.

When first starting out, focus on practicing the basics – like centering clay on the wheel, achieving an even thickness, and smooth edges. Simple cylinder shapes and small bowls are great starter projects. Accept that mistakes and imperfections are part of the learning process. With regular practice at home, your skills will steadily improve.