Glossary

Tannin

a clear to slightly yellowish powder, mainly extracted from Chinese gallnuts. Tannin is a tanning agent and is used, when dissolved in water, as a pre-stain when chemically staining woods low in tanning agents. The pre-stained surfaces take on colour when subsequently stained with metal salt solutions or alkalis. Tannin dissolves in water, ethyl alcohol and diethyl ether

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