Efflorescent materials

Take a portion of the crystals (or some of the material in crude form) and allow it to effloresce freely in a warm place. Put it in a roomy desiccator in place of the usual drying agent (calcium chloride). Place the wet crystals in a suitable container and support them over the effloresced material in the desiccator (Fig. 2). There are... 

THE techniques OF conservation and conservation science and the techniques of anthropology, archaeology, and art history are often used to solve very specific problems such as the removal of efflorescent materials from the surface of a wall painting or the determination of the provenance... 

Tetrasodium hexakiscyanoferrate decahydrate [14434-22-1], Na4[Fe(CN)g] IOH2O, or yellow pmssiate of soda, forms yellow monoclinic crystals that are soluble in water but insoluble in alcohol. It is slightly efflorescent at room temperature, but the anhydrous material, tetrasodium hexakiscyanoferrate [13601 -19-9], Na4[Fe(CN)J, is obtained at 100°C. The decahydrate is produced from calcium cyanide, iron(II) sulfate, and sodium carbonate in a process similar to that for the production of K4[Fe(CN)g] 3H2O. It is used in the manufacture of trisodium hexakiscyanoferrate, black and blue dyes, as a metal surface coating, and in photographic processing. 

Cobalt(Il) sulfate heptahydrate [10026-24-17, CoSO is a reddish pink monoclinic crystalline material that effloresces in dry air to form the... 

Visible exudation or efflorescence on the surface of a plastic caused by plasticizer, lubricant, etc. Spacer or filler material in a mold. 

Efflorescence. The solvent properties of water also causes efflorescence, a phenomenon whereby soluble or slightly soluble substances migrate from the interior of porous solids to the surface, where they precipitate. Efflorescence is an important factor in the decay and disintegration of many rocks, and of human-made porous materials such as ceramics, and even of some types of glass. On archaeological objects, efflorescence generally occurs mostly as a white, powdery, but sometimes consolidated accretion on the surface of the objects. Calcite, a form of calcium carbonate, is one of the most common substances to effloresce on archaeological ceramics. 

The term alumen plumosum has had a long association with asbestos. Alumen (= alum) is a general term for naturally occurring hydrous alkali aluminum sulfates. These are efflorescent mineral materials of fibrous, feathery appearance. Confusion with the more durable silicate composition asbestos was not settled until 1741, by Tourneforte following a visit to asbestos deposits in Asia Minor. 

Alumen plumosum A Latin name given to the fibrous and feathery types of natural alum (hydrous alkali aluminum sulfates) and other efflorescent natural sulfates. Because of visible similarity, these materials were confused with asbestos by some early writers, and the term remained in use as a synonym of asbestos for many years. 

Concrete dampproofers are integral admixtures that alter the concrete surface so that it becomes water repellent, or less wettable . This is illustrated in Fig. 4.1, which shows a close up of a water drop on a surface of a concrete that has had a dampproofer incorporated into it. This water repellency conferred on the concrete is only effective in preventing water from entering the surface when the applied pressure is small, e.g. rainfall in windy conditions, or capillary rise. The latter effect is shown in Fig. 4.2. In view of this, these materials are used normally for improving the quality of concrete pavers, tiles, bricks, blocks and cladding panels where the additional benefits of reduced efflorescence, the maintenance of clean surfaces and the more even drying out of adjacent bricks and panels are also obtained. 

The Owens Lake brine analysis of Table V Indicates that the Na/S ratio should be approximately 3.8 for lake bed materials, which agrees quite well with the ambient ratio measured at Keeler. The above data suggests that airborne sulfur aerosols measured in the Owens Valley are in the form of sulfates which are suspended from the efflorescent crust on the Owens Lake bed. Therefore, if we assume that all the sulfur measured at each site is in the form of sulfate, then during a dust storm, the sulfate standard for the state of California (25pg/m ) is violated near the Owens Lake. It should be noted that the sulfate standard was developed for very fine acidic aerosols. The sulfates measured here are larger and basic particles, so their toxicity may be different from particles for which the standard was written. The calculated sulfate levels at each site during a dust storm are listed in Table VI. 

The Hungarian soda has been known from the time of the Roman dominion as a product of the efflorescence of the soil. The crude soda or szekso is collected by scraping, and sold to the refiners, who lixiviate it with water evaporate the soln. to dryness and fuse the mass. When cold, the product is broken up and marketed. It is used locally at Szegedin in the manufacture of soap. J. Moser has published an analysis of the raw material, and S. Sehapringer, two analyses of the Hungarian soda. The former s analysis is ... 

Efflorescence. The property of some hydrated crystals to change upon exposure to air to a mealy or powdety suhstance either on the surface or throughout the material. This is due to partial or complete loss of water of crystallization... 

Tetrapotassium hexakiscyanoferrate trihydrate [14459-95-1], K4[Fe(CN)J H20, is an efflorescent lemon yellow compound known as yellow prussiate of potash. The anhydrous material [13943-58-3] is obtained at 70°C. The compound is soluble in water and acetone, but insoluble in alcohol, ether, and ammonia. It is oxidized to hexakiscyanoferrate(3—) by oxygen in acidic solution, or by oxidants such as ozone, C, Br2, H202, or MnO. A large number of insoluble or slightly soluble mixed salts of the general formula K2MII[Fe(CN)(5] and KMIII[Fe(CN)(5] are known, eg, M11 = cobalt(II)... 

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