Onggi: Korea’s “Breathing” Jar — Why This Traditional Pot Is Essential for Fermentation
What Is Onggi and Why It Matters Onggi (옹기) are traditional Korean earthenware jars used for storage and — most famously — for fermenting food. Think of them as more than pottery: they’re living tools that subtly influence the microbes, gases, and moisture inside, creating ideal conditions for foods like kimchi, doenjang (soybean paste), gochujang, soy sauce, and fermented seafood. Modern research now confirms what generations of Korean cooks observed by practice: onggi’s physical properties actively help fermentation develop desirable flavors and microbial communities. Onggi’s Key Feature: Breathability (What Koreans Call “Onggi Breathing”) What does “breathable” mean? Onggi are made from clay bodies fired at relatively low temperatures with deliberate inclusion of grog (crushed fired clay or sand) and specific glazing techniques. The result is a microporous structure — tiny interconnected pores and channels in the clay body — that allow gases (like carbon dioxide and small amou...