The acidity comes from tannic and gallic acids. Tannins are removed using PVPP, haze-forming proteins by using silica or tannic acid. It produces tannic wines with a spicy, plummy flavour. Lagrein produces wine with high acidity that are highly tannic. The tannic nature of Cabernet Sauvignon is an important winemaking consideration. Some examples of these antagonists are caffeic acid, chlorogenic acid, and tannic acid. The very tannic Nebbiolo grape may spend four or more years in oak. Common processes involved chemicals such as glycerin, magnesium nitrate, tannic acid and albumen. The area around Cahors produces wine, primarily robust and tannic red wine. The area is known for producing powerful, tannic red wines. Upon inhalation, tannic acid may cause respiratory tract irritation. The name is derived from oak galls, which were historically used to prepare tannic acid. Eels from clear water are often lighter than those from dark, tannic acid streams. Citrate ions or tannic acid function both as a reducing agent and a capping agent. In furniture-making, Ammonia fuming was traditionally used to darken or stain wood containing tannic acid.