Ceramic Glazes: What They Are, How They Work, and What You Need to Know
When you see a smooth, shiny bowl or a vibrant mug, what you’re really seeing is ceramic glaze, a glass-like coating fused to pottery during high-heat firing. Also known as pottery glaze, it’s not just decoration—it’s what makes clay waterproof, food-safe, and durable enough for daily use. Without it, your favorite mug would leak, crack, and absorb stains in weeks.
Behind every beautiful glaze is glaze chemistry, the science of mixing silica, fluxes, and colorants to create stable, predictable surfaces. Silica forms the glass base. Fluxes like feldspar or borax lower the melting point so the glaze flows at kiln temperatures. Colorants—cobalt, iron, copper—add hue but can behave unpredictably depending on oxygen levels and firing speed. Get the balance wrong, and your glaze might crawl, bubble, or even leach toxins into food.
That’s why ceramic firing, the process of heating pottery to specific temperatures for precise durations is just as important as the glaze recipe. A glaze that melts perfectly at cone 6 might stay powdery at cone 06. Overfire it, and it runs off the piece. Underfire it, and it stays rough and porous. Kiln logs, pyrometric cones, and even the type of kiln (electric vs. gas) change how glazes behave. Many potters spend years testing the same glaze on different clays, just to nail the look.
And then there’s glaze safety, the critical check that ensures your finished piece won’t harm anyone who uses it. Lead and cadmium were once common in bright glazes, but now they’re banned in foodware in most countries. Even some modern glazes can release metals if not properly fired. If you’re making mugs, plates, or bowls, you need to know if your glaze is certified food-safe. That means testing for leaching, checking manufacturer data, and firing to the right temperature—not just guessing.
Most of the posts in this collection don’t talk about pottery—they talk about medicine. But the same principles apply: what you put on or in your body needs to be understood, tested, and handled with care. Just like a glaze can turn toxic if fired wrong, a drug can turn dangerous if misused or misunderstood. Whether it’s how azathioprine triggers lupus, how caffeine affects muscle spasms, or how vitamin D deficiency causes headaches—every effect has a cause, and every solution needs the right conditions.
Here, you’ll find real stories and data about how substances interact with the body—just like how glazes interact with clay and fire. You’ll see what happens when expectations shape side effects, when alternatives work better, and when a little change in dosage or timing makes all the difference. There’s no magic formula. Just science, experience, and attention to detail.
