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Question

Is it true that you must clean a vehicle far more thoroughly prior to painting it with water-dispersible CARC than with the solvent borne CARC?

Answer

This is a good question. Solvents play an important role in CARC topcoat surface adhesion by emulsifying surface impurities, such as oil or grease on the substrate. Water dispersible CARC replaces a percentage of solvents with water. Replacing solvents in CARC with water adequately serves the purpose of reducing the coating to a sprayable viscosity. However, water is not nearly as forgiving as solvents when a substrate has been improperly prepared. Coating equipment with CARC is much more involved than just applying the CARC topcoat. The CARC coating process consists of four distinct steps, each of which is critical to the performance of the overall system; cleaning, pretreating, priming, and topcoating. Regardless of whether solvent or water dispersible CARC topcoat products are used the risk associated with not performing these necessary steps is a coating film that may prematurely fail to protect the vehicle and possibly the troops operating that vehicle. To answer your question more concisely, water dispersible CARC should not require additional cleaning if all four steps in the CARC system are adequately performed. If a painter is spraying water dispersible CARC over an improperly prepared surface it will not be as forgiving as solvent CARC. Oil and water do not mix and when they come in contact instant separation will occur. Spraying water dispersible CARC over a contaminated surface is not a good idea because the water will not lift or emulsify the surface contaminants like solvents may be able to do.

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