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COATINGSPRO SURFACE PREP 2017 9 differ from model to model and brand to brand, cold pressure washers are well suited to handle almost any job that requires washing away dirt and mud. However, if grease or grime covers a surface that needs to be prepped for a coating, cold pressure washers won't do a sufficient job," explained Dan Leiss of Jenny Products. To cut through grease and grime and loosen them from the surface, a hot pressure washer may be needed. Jenny Products and Hotsy are among the companies that offer hot and cold pressure washers that can be used on a variety of substrates. According to Leiss, while pressure washers can be used to clean almost any surface, users need to be aware of the impact high pressure can have on individual substrates. "Higher pressures can damage some softer or more porous surfaces. It's best to always test a pressure washer on the surface to make sure no ill effects happen before moving forward with a full cleaning," stated Leiss. In some instances, the circumstances call for ultra-high pressure (UHP) waterjetting to remove old coatings and contaminants. "W hat we've seen over WJTA-IMC A's history is the emergence of waterjetting as a viable and economic alter- native to other forms of blasting for an increasing number of coating types and applications. Occupational safety aspects and the smaller, more easily contained waste streams make waterjetting an attractive option for many contractors," said LeAnn Hampton of WJTA-IMC A. Waterjetting removes debris at the surface of steel but typically should be done only after oils and greases are removed; it is not used to create a surface profile. To create a surface profile on steel, high pressure water is combined with an abrasive media, referred to as water blasting. On concrete, however, high pressure water alone can be used to penetrate the surface to remove waterproofing elastomeric membranes and deteriorated concrete and to create light scarification. Jetstream of Houston and AquaFlow are two companies that offer high pressure waterjetting equipment. Complex Cleaning W hen preparing steel surfaces to receive a coating material, special attention must be paid to removing soluble salts. "Residual surface salts left on the surface during surface preparation is one of the leading causes of premature coating failures. A ny added cost associated w ith decon- taminating surfaces of salts is insignificant relative to the impact of achieving full coating life cycle performance," said Hap Peters of CHLOR*R ID. To eliminate soluble salts Water can be key. "Occupational safety aspects and the smaller, more easily contained waste streams make waterjetting an attractive option for many contractors," said LeAnn Hampton of WaterJet Technology Association/Industrial & Municipal Cleaning Association (WJTA-IMCA). Surface Preparation