General tannic acid

Astringents are designed to dry the skin, denature skin proteins, and tighten or reduce the size of pore openings on the skin surface. These products can have antimicrobial effects and are frequendy buffered to lower the pH of skin. They are perfumed, hydro-alcohoHc solutions of weak acids, such as tannic acid or potassium alum, and various plant extracts, such as bitch leaf extract. The alcohol is not only a suitable solvent but also helps remove excess sebum and soil from the skin. After-shave lotions generally function as astringents. 

Stabilization of crude and purified anthocyanin extracts from agai by the addition of tannic acid resulted in a 65% half-life increase of anthocyanins from the crude extract and 610% of the half-life of the purified one. Although tannic acid was considered an efficient copigment,in general all cinnamic acids give unpleasant odors and tastes to solutions. 

In dentistry, when astringents and antiseptics are used to harden and dry tissues of the pulp and root canal so that the tissues are resistant to infection, they are termed as mummifying agents. It is used in certain dental procedures when it is not possible to completely remove the pulp and contents of root canal. For this, generally a combination of various mummifying agents are used in the form of paste or semi-liquid preparation like tannic acid glycerine. 

While tannins probably vary in composition, the type generally termed tannic acid is a pentadigalloylglucose for hydrolysis yields diagallic add and glucose. 

In another series of experiments electrodes fabricated from several carbon materials were tannic acid-dispersed and performance-tested in DC-1 against silver-silver chloride. Generally it was necessary to soak the electrode (after drying) in a concentrated sodium chloride solution to coagulate the carbon more completely before mounting in the cell. In this series, a feed solution of 0.03V sodium chloride, identical applied voltages (0.30... 

Most basic and acid dyestuffs are fixed without aid by animal fibres vegetable fibres, on the other hand, require the intervention of a special mordant. Tannic acid is generally used along with basic dyestuffs, as it forms insoluble salts with these compounds. 

Night Blue is obtained from paratolyl-a-haphthylamine (P-C7H7NHC10H7) and tetramethyldiamidobenzophenone. These dyestuffs come into commerce as hydrochlorides. They are beautiful blue dyestuffs, easily soluble, and dye cotton prepared with tannic acid similarly to methylene blue, but unfortunately the shades produced are not very fast to light. In general their reactions resemble those of the rosaniline dyestuffs. Alkalies precipitate a reddish-brown base, and acids turn the blue colour to yellow. 

General Reactions of Alkaloids (Section 670).—Dissolve the amount of quinine sulphate that can be held on the point of a pen-knife in about 20 cc. of water. Observe the appearance of the solution. Add to 2 cc. of the solution drop by drop, a dilute (1 per cent) solution of tannic acid. Repeat using solutions of phosphomolybdic acid, picric acid, iodine in potassium iodide, and potassium mercuric iodide. The last-named solution can be prepared by adding an excess of a solution of potassium iodide to a solution of mercuric chloride. 

While for most adults and children, cold sores generally clear up without treatment in seven to ten days, pain may be alleviated by home remedies such as avoiding spicy or acidic foods, applying ice or warmth to the blisters, or applying a moistened tea bag to the area, as it has been suggested that tannic acid (a chemical found in tea) may possess antiviral properties. Unfortunately, the HSVl infection itself cannot be cured. It is recommended that patients wash blisters gently with soap and water and dry thoroughly to prevent secondary bacterial infections. 

Sodium Tannate. Sometimes used as a deflocculant for clay slips the effect is marked, only a small proportion being required. The material used for this purpose is generally prepared from NaOH and tannic acid the former should be in excess and the pH should be about 8-9. 

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