Mystery solved: where does the dirty skin on your cup of tea come from?

“The phenols from fruit and vegetables react with the lime in tea water, creating a hard film on the tea. The more lime, the thicker and firmer the layer. If one would use pure or demineralized water, not a hard layer but a thinner liquid layer”, explains Van Dyck. “But we don’t see such a liquid layer and it doesn’t bother us.”

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