a sulphiting process which transforms the phlobaphenes into completely soluble tannins. The cold soluble quebracho extracts are the most universally known and used types. The chemical structure of these extracts can be described as polymers of epicatechin. The main properties of these extracts are: a very rapid penetration, a high tannin content and a relatively low percentage of non-tannins. The rather low acid and medium salt content characterise them as mild tanning extracts (low astringency). Quebracho tannins give an important added value to the quality of leathers, such as vacchetta, belts and garments, making them more compact and tear resistant with a pleasant touch. The sulphited quebracho extract may be carcinogenous in mice. Other recent studies show that quebracho tannins present a strong anti-mutagenic activity. The heartwood contains from 20 to 30 percent tannin and 3 or 4 percent water-soluble nontannin. It is said to not ferment. According to King and White (1957), the hydrolysable tannins and gallic acid found in the sapwood constitute the raw material for the biosynthesis of the condensed tannins found in the heartwood. Fustin (predominantly (-)-Fustin 66%), (-)-7:3':4'-trihydroxyflavan-3:4-diol ((-)-leuco-fisetinidin), (+)-catechin, gallic acid, fisetin and 2-benzyl-2-hydroxycoumaran-3-ones have been isolated from the heartwoods of Schinopsis balansae, Schinopsis quebrachocolorado and from commercial quebracho extract. Quebracho tannin is rich in profisetinidins and prorobinetidins. The expected masses found in mass spectrometry in negative mode in quebracho tannin are 289, 561, 833, 951, 1105, 1377, 1393, 1651 and 1667. In Quebracho , the sugars and the lignins are thought to be covalently linked to the condensed tannins. Quebracho tannin is also sold as an enological tannin. The quebracho tannins structure is very similar to that of grape tannins, making them a desirable alternative to consider comparatively because they are much less expensive to produce than grape tannins. Myo-inositol and arabitol are detected in tannins from quebracho. Researches are being made to develop an eco-friendly anti-biofouling paint from quebracho tannin. The tannic acid, in the form of alkalized salts, was extensively used as a deflocculant in drilling muds in 1940s-1950s, until it was replaced with lignosulfonates. Its red color gave the mixture the name red mud. Quebracho tannin acts as flocculant agent to remove surfactant as sodium dodecylbenzenesulfonate in water treatment. For its polyphenolic structure, quebracho tannin is widely studied for particle boards, plywood and fiber board gluing. The Argentine companies Unitán and Silvateam are the main leaders in quebracho tannins production.