Surface Preparation
Surface Preparation Why Proper Surface Preparation is Vital to Maximum Performance of Paints & Coatings No matter how good the coating, its effective service life can be shortened by insufficient or ineffective surface preparation. For maximum performance of a paint or coating, the surface must be adequately prepared to effect positive and long lasting adhesion of the coating to the substrate. This results only when contaminants (such as mill scale, rust scale, chemicals, grease, oil, dirt, weld splatter and failed old coatings) that adversely affect adhesion are removed. Obviously, a properly selected coating system will outlast an improperly selected system under the same conditions. But with cor- rect surface preparation, the properly selected coating system delivers maximum performance through an even longer service life, further reducing the annual cost of protective maintenance. CONCRETE I) General Concrete is composed essentially of three materials: cement, water and aggregates. A fourth material, called an admixture, is sometimes added for a variety of specific purposes such as entrainment of air, acceleration or retardation of setting and hardening. Cement makes up 10 to 15% of the total volume, aggregate occupies about 66 to 78%. The remaining volume is water. The water in concrete serves a dual function. It first converts the dry cement and aggregates into a plastic mass. The water then reacts with cement chemically to hydrate and harden the mass. The aggregate, which may be fine or coarse, is bound together by the hydrating cement and gives cured cement its basic strength. A mixture of cement and water with no aggregate is weak, brittle, and not a suitable substrate for paint.
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