Clay Waterproofing: Tea Tannin

I recently filled some of the clay cups I made with tea overnight to see how well they would hold the liquid if they were unglazed. Unfortunately the cups leaked slightly and so invoked a great deal of thinking into how I could waterproof them. As I wish to leave my clay work with bare and untreated finish I looked into traditional Chinese methods. Yixing teapots have the same finish that I desire and so from looking into their use I learned that a very high fire combined with a “tea wash” could work.  As well as researching the Yixing methods I asked a friend, and past social digital student, about his use of tea as a tanning aid in leather. He explained to me that the oils and tannin in the tea help to loosen up the leather and waterproof it. This is another reason to try bathing my clay work in tea.oolong_043Tannin is a bitter plant polyphenolic compound that binds to and precipitates proteins. In human dietary compounds is most commonly found in tea and wine and aids in their aging. I began to prototype this concept in the hope that many bathes of tea will build an oily layer in the clay, and hence water proof it. I did this my filling two tea pots, one with Chinese gunpowder green tea and the other with Chinese Formosa oolong. These two teas have a very distinct small and so allowed me to also prototype the effects of any scent that would be left behind.Photo 11-02-2014 18 08 29Photo 13-02-2014 19 49 28Photo 11-02-2014 18 08 37After the clay had soaked for a day or two I removed them to observe the effects. In most cases there is a strange discolouration as well as a musky tea smell. As of yet there is no effect on the waterproofing front, but I intend to soak the clay in multiple stages to hopefully build up the tea oils within the clay.Photo 13-02-2014 19 49 10Photo 13-02-2014 19 49 47

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