The Best Material for Dishware

A long journey of studying materials, as well as theory and practice in the science of ceramics, has led me to work exclusively with stoneware masses. Stoneware is highly plastic, strong, and has the lowest water absorption percentage. Plus, stoneware masses hold temperature better! You've probably noticed that you can take a scorching cup with a cold drink straight out of the microwave? Well, that's not the case here! And of course, they are exquisitely beautiful and simply made for sculpture.

I'll tell you about what clay is as a phenomenon and how it is born in nature in another article. For now, let's talk a bit about ceramics! Ceramics is the name for any clay that has undergone firing. The type of clay doesn't matter. So, the exclamation "Your ceramics and porcelain are very unusual" is incorrect. Porcelain is also ceramics, since essentially it starts as clay.

And the most important properties of ceramics are porosity and thermal conductivity!

Porosity depends on the type of clay and the firing temperature. Why is this important? Fired clay can both absorb water and allow it to pass through. This process is called water absorption. And it directly depends on the pore size. The lower the firing temperature, the finer the pores remain. How ceramics absorbs water is very noticeable after the first "biscuit" firing. That's exactly why it's called that. At this moment, high water absorption is very convenient because it makes applying glaze much easier. That's where the advantages of high water absorption end.

From there, only disadvantages. The dishware will absorb liquid along with everything in that liquid. Which means bacteria along with food particles will find a cozy home in the wide, comfortable pores of your cup.

Porous clays are those fired at temperatures of 900–1150 degrees. At such temperatures, earthenware masses (majolica) are fired. These materials have water absorption over 3%, usually 10–12%. For majolica production, low-melting clays are typically used. Examples include terracotta and red clay. Items from such clays are less durable, but their production uses less electricity and wears the kiln less. Any item from such clay that contacts food or water must be glazed!!!

Non-porous clays are those fired at significantly higher temperatures—from 1180 to 1420 degrees. For example, porcelain and porcelain stoneware masses. These materials have minimal water absorption, less than 3%. The exception is earthenware :) Despite firing at high temperatures (1200–1250 degrees), it retains high porosity and water absorption of 8–12%.

Porcelain is made from a mixture of kaolin, clay, feldspar, and quartz. Its water absorption is about 0.1%. The composition of porcelain is such that the viscous melt of feldspar during firing not only binds quartz particles (which turns into liquid glass during firing), but also transforms flat kaolin crystals into long mullite crystals, which give porcelain items high strength and allow for the production of thin, translucent pieces. Porcelain mass is non-plastic. Can porcelain be low-temperature? No. Feldspar creates the necessary melt for mullite formation only at high temperatures. Porcelain can be used with or without glaze—it's safe either way! 🙂

Traditional stoneware masses consist of a mixture of clay, feldspar, and quartz, with water absorption at the recommended temperature of less than 3%. During firing, the quartz melts, becoming liquid and turning into glass that penetrates the tiniest pores of the clay. As the fired items cool, the molten glass hardens and binds the clay particles even more. The result is an extremely dense ceramic structure with low porosity. Ceramic masses are plastic and exhibit less shrinkage during firing than porcelain. They look great with glaze and can even be used without it— that's safe too!

Can stoneware masses sometimes be low-temperature? Possibly. If the composition includes low-temperature clays and fluxes, for example, some red clays. In doing so, they retain their properties.

The question arises: does pore size matter if the item is glazed? It actually does. Sometimes cracks (crazing), chips, and similar defects appear on the glaze surface. They may not show up right away, but over time, during use. Your favorite vase or cup might start absorbing liquid, bacteria could settle in the pores, and a puddle might form on the table under a vase with flowers...

Some of my friends and clients have asked me: "I bought a vase. And now, when I put flowers in it in the evening, there's always water under it in the morning... Why?" Because... majolica 🙂

I believe a cup shouldn't turn into a Petri dish. So for tableware, if it's going to be used, it's better to prefer porcelain and stoneware dishware. Vases should also be chosen from stoneware, porcelain, or glass.

Majolica is better suited for decorative items—sorry for those words, majolica fans :) Figurines, wall plates, small vases, sculptures, or maybe nut bowls. It's best not to use it anywhere else. But if you've fallen in love with a majolica cup, please wash it in the dishwasher and avoid the microwave! The dishwasher removes food residues better, making the dishware more hygienic. In the microwave, such items heat up much faster than ceramics. So in the end, you might end up with scalding-hot cup with cold tea that's impossible to hold.