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Paint Technology Handbook by Rodger Talbert download in ePub, pdf, iPad

Blasting operations can be manual batchAs the water

Other blast materials are manufactured using a variety of metal and nonmetal compositions such as steel, iron, aluminum oxide, silicon carbide, plastic, wheat starch, and glass bead. Pretreatment eliminates reactions between metals and between coatings and metals. Chelants do a very good job of breaking down smut whereas alkalis, solvents, and most acids are not very effective. Solvents are typically not effective.

Adequate coverage with the coating material is critical, if extended life is expected over a blast-only surface. Over-sprayed solution can be run straight to drain or captured, filtered, and reused. However, mechanical cleaning alone will not provide undercoat corrosion resistance or extend the life of the finished product. The cleaner may be alkaline, acidic, neutral, solvent, or an emulsion.

Many systems use some immersion cleaning along with spray stations. Immersion cycle times are typically longer than spray cleaning methods, because spray systems have the added cleaning power of mechanical energy from spray pressure. Acids will turn the soap to a semisolid mass and make rinsing more difficult. Inorganic materials include siloxanes, silicones, and sulfurized polymers. Pressure-blast systems use a pressurized vessel to deliver the media, providing higher nozzle velocity that can clean the surface much faster than a suction system.

Blasting operations can be manual batch systems or automated in-line systems. As the water passes through the coil, it becomes progressively hotter as steam is formed. Some shapes may be difficult to clean by hand. Acceptable in noncorrosive environments where long-term coating life is not expected. Dip systems normally require higher chemical concentration than spray systems and longer operation times, even with agitation.