Water rinsing

Finish removers are appHed by bmshing, spraying, troweling, flowing, or soaking. Removal is by water rinse, wipe and let dry, or solvent rinse. Removers may be neutral, basic, or acidic. The viscosity can vary from water thin, to a thick spray-on, to a paste trowel-on remover. The hazard classification, such as flammable or corrosive, is assigned by the U.S. Department of Transportation (DOT) for the hazardous materials contained in the remover. 

Emulsifiers. Removing the remover is just as important as removing the finish. For water rinse removers, a detergent that is compatible with the remover formula must be selected. Many organic solvents used in removers are not water soluble, so emulsifiers are often added (see Emulsions). Anionic types such as alkyl aryl sulfonates or tolyl fatty acid salts are used. In other appHcations, nonionic surfactants are preferred and hydrophilic—lipophilic balance is an important consideration. 

Paraffin wax vapor barriers are used in water rinse removers that can disperse the wax without coating the substrate. In soak tank applications, water is sometimes doated on top of an ad-solvent, neutral pH, nonwater rinse remover to prevent evaporation. Flotation devices that cover the exposed surface area may be used with other formulas. 

A detergent that is compatible with the remover formula must be developed for water rinse removers. Anionic or nonionic surfactants should be selected, depending on the pH and intended application of the remover. 

Wetting agents are used to make a water rinse remover. Water rinse removers are normaUy used for removing paint, where the surfactants help remove paint and remover from the substrate. Solvent rinse removers or wipe and dry formulas may be used for stripping clear finishes. A typical petroleum and oxygenate formula is as foUows (10). 

Environmental Impact. The volume of waste remover from these products is remarkably increased when compared to methylene chloride, petroleum, and oxygenate removers, since both /V-methy1pyrro1idinone and dibasic esters have low vapor pressures. Recovery of the remover after use is difficult because the finish is tesolubili2ed by the remover. A representative dibasic ester formula appears below for a thickened water rinse finish remover. 

Cold Exhaust Dyeings Fiber-Reactive Dyes. Start at 25—30°C optionally with a sequestrant and maintain. The dye is added over 5 min, then there is portionwise addition of salt every 10—15 min, increasing the size of the addition each time over 1 h. The amount of salt used (10—100 g/L) depends on the depth of shade. After the final addition of salt, wait 15 min, portionwise add soda ash (10—20 g/L) over 15 min, and continue dyeing for 30—45 min. Drop dyebath, cold water rinse, and use a sequence of hot washes to remove all loose "unfixed" dye. 

Acid Dips and Acid Pickles. Acids are used to remove inorganic soils. A distinction is made between acid dips and acid pickels. Where there is no mst or scales, a dilute acid dip is used for activation and as a rinse aid. Caustic residues from cleaners are notoriously difficult to remove with water rinsing alone. By contrast, strong acid pickles are used to remove mst and scale. 

After being removed from the nickel bath, the ware is dipped into a hot or cold water rinse, quickly removed, and then transferred to a neutralizing bath where the last traces of acid are removed. Neutralizing using a solution of sodium carbonate (soda ash) and borax is common. 

The process is then resumed. Meanwhile, regeneration is occurring by a similar flow system in the regeneration tank, from which the regenerated ion exchanger is transferred periodically to the hopper above the water-rinse tank. In the latter, the resin particles are fluidized to flush away fines and accumulated foreign matter before the resin is returned to the adsorption tank. 

Water rinsing To rinse, wash the surface in clear, continuously running water to remove all traces of acid from the surface. Two or three dips at room temperature will be sufficient. The details of tank will be similar to those for the acid tank but without any heating arrangement. 

Water rinsing To rinse, wash the surface in clear water an MS tank with a thickness of 3-4 mm is adequate. It may, however, be provided with corrosion-resistant paint to extend its life. 

When de-rusling is adopted after HCI pickling, the second water rinsing, as reeommended above, is not essential as the traces of chloride, if any, will be neutralized in the de-rusting tank, which is a phosphoric acid-based rust solvent. 

Only one water rinsing, with a few extra dips, is adequate... 

The phosphaled surface must be transferred to the water rinsing tank without delay. 

Mercuric iodide (red) [7774-29-0] M 454.4, m 259 (yellow >130°), b 350°(subl), d 6.3. Crystd from MeOH or EtOH, and washed repeatedly with distilled water. Has also been mixed thoroughly with excess 0.00IM iodine solution, filtered, washed with cold distilled water, rinsed with EtOH and Et20, and dried in air. POISONOUS. 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Corrosive, particularly when diluted. Attacks most common metals, including most stainless steels. Excellent solvent for many synthetic resins or rubber Stability During Transport Stable Neutralizing Agents for Acids and Caustics Dilute with water, rinse with sodium bicarbonate solution Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

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