Valonia(redirected from valonia oak)
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the acorn cup (calyx) of several species of oak (Quercus vallonea from Asia Minor and Q. macrolepis from Italy and Greece). Valonia is 35-40 percent tanning substances, or tannins, which are used to tan and strengthen sole leather. Tannins are extracted from valonia by water at a temperature of 50-60° C. (They decompose at higher temperatures.) Valonia is usually used along with acorns; there is 29 percent tannin in the mixture. In the USSR the Q. vallonea and Q. macrolepis can be grown in western Transcaucasia and southern Crimea.