How Porcelain Is Made with Clay Glaze and Fire
zzwPorcelain is made through a sequence of controlled changes: raw minerals become a workable clay body, the body becomes a dry form, glaze becomes a glassy surface, and heat locks the structure together. The process sounds tidy on paper. In a real workshop, every stage introduces decisions and possible failure.
1. Preparing the body
Porcelain bodies commonly combine kaolin or other clays with feldspathic and siliceous materials. The mix is processed with water, screened, and de-aired so it behaves consistently. Some workshops use plastic clay for wheel throwing; others use liquid slip for casting. The body determines how thin a wall can be made, how much a form will shrink, and how it responds to glaze.
2. Forming and drying
Throwing, slab building, pressing, and slip casting produce different visual clues. A thrown cup may show subtle rings inside. A cast form can repeat complex contours efficiently. After shaping, the piece must dry slowly enough to avoid cracks and distortion. Handles and spouts are attached at carefully chosen moisture levels so they shrink with the body instead of pulling away.
3. The bisque or first firing
Many porcelain pieces receive a first, lower-temperature firing that turns the fragile greenware into a porous ceramic ready for handling and glazing. Some production systems glaze raw ware directly. Either way, the maker is balancing strength, absorption, and the risk of trapping moisture.
4. Glazing and decoration
Glaze is a carefully formulated coating that melts into a glass-like surface during firing. It may be dipped, poured, sprayed, or brushed. Thickness matters. Too much glaze can run or obscure detail; too little can leave dry patches. Decoration may be painted under the glaze, painted over it, carved through it, or created by molded texture.
5. High-temperature firing
The kiln schedule is a recipe with a long memory. The firing rises gradually, holds at selected temperatures, and cools in a controlled way. During the peak, the body vitrifies and the glaze melts. Cooling can be just as consequential as heating; sudden changes create stress and cracks. Kiln furniture, stacking, and placement influence the result as much as the programmed temperature.
6. Sorting, finishing, and packing
After firing, each piece is inspected for warping, glaze defects, sharp edges, and fit. “Seconds” may be sold at a different grade, while other pieces are rejected. Feet can be sanded, marks added, and surfaces cleaned. Good packing is the final manufacturing step for an online order: a beautiful object that arrives broken has failed its journey.
For customers, the useful questions are simple: Is the piece food-safe for its stated use? Is it microwave or dishwasher suitable? What variations should be expected? A responsible product page answers those questions without pretending every handmade surface will be identical.
Continue with the Changnan Objects story or browse small porcelain objects selected for everyday use.
FAQ: Questions readers often ask
Why does porcelain shrink?
Water leaves the clay during drying and firing, while particles pack more tightly and the body vitrifies. The exact shrinkage depends on the recipe and process.
What is a glaze pinhole?
A pinhole is a tiny opening in the fired glaze, often caused by gases escaping from the body or glaze. A maker may accept, repair, or reject it depending on the intended grade.
Can porcelain be repaired after firing?
Small chips can sometimes be repaired cosmetically, but a repaired food-contact surface should be treated cautiously. Follow the maker’s care guidance.
Sources for further reading: Ceramic Arts Network, porcelain process · V&A, how ceramics are made
