Tannins and human health: a review. Chung KT, Wong TY, Wei CI, Huang YW, Lin Y. Department of Microbiology and Molecular Cell Sciences, University of Memphis, TN 38152, USA. Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods.
How to Cast Jewelry. Jewelry casting is a process of making jewelry pieces that involves the pouring of liquid metal alloy into a mold. It is usually referred to as lost-wax casting because the casting mold is created using a wax model that is melted away to leave a hollow chamber in the middle of the mold.
Real gold jewelry is made of a solid gold alloy, whose gold content is above a certain threshold. In the United States, for example, pieces containing less than 58.3% gold (10 karats) are not considered gold for commercial purposes. What people usually refer to as fake gold is jewelry that is made of another metal (such as nickel, copper, silver, etc.) and covered with a layer of gold (gold plated) or with a thin gold sheet (gold filled). How to Tell If Gold Is Real. Below are some of the more reliable ways to test jewelry for gold: Acid Test