Shigaraki clay is a type of clay that contains feldspar rocks, which is special since during the process of chemical weathering, the slightly acidic water is transforming feldspar present in the granite rocks into kaolin which is a clay mineral. Due to a specific level of humidity and speed of river flow, this process is not fully outplayed therefore the sedimentary clay layers still contain a variable level of these feldspar-rich rocks. This clay used to be found in the 4 million year-old sediment deposits of lake Biwa which snaked its way many kilometers westwards from the village. Following the 70’s when this style of pottery was very popular, it is now a rare commodity to be found in the wild. There are some hills left that contain some of this now very precious clay, although they are all now privatized. During the firing of this clay in a traditional Anagama wood-fueled kiln, the Feldspar rocks liquify due to its low melting temperature – this results in glass-like drops bleeding out of the clay.
I went out into the mountains, hiked upwards along the many little mountain streams that would eventually flow into the new Lake Biwa. I attempted to understand the process of the emergence of this specific clay. Here the same process was taking place that took place millions of years ago elsewhere to form the feldspar rich clay deposits in the area around the village of Shigaraki. The soft water gliding seemingly softly over the granite rocks, slowly sneaking its way into the rocks’ crystalline matrix with the help of some acidity – where the process of hydrolysis is altering feldspar into kaolinite, with potassium ions, bicarbonate and silica in the solution as a byproduct. The seemingly invincible-looking granite rock is now crumbling apart like sweet meringues. Combining this crumbling granite with some natural iron-rich red clay I found along one of my hikes, resulted in a similar experience as the legendary Shigaraki clay – from which the feldspar rocks bleed out of the clay during the wood-firing.
Re-making, Japan. (2018)
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