Coatings are substances that when applied to various substrates improve the functionality and or aesthetics of the substrate. High performance coatings are just that — they improve the performance of the substrate. Some of the various physical characteristics that they improve include chemical resistance, abrasion or heat resistance, resistance to water penetration and corrosion resistance.
When selecting high performance coatings, consider them as a system, each part must be compatible with the other. The substrate or material to which the coating is applied must be compatible with the primer or undercoats and the top or finish coat. Any incompatibility between coating and substrate can result in premature deterioration and a reduction in the physical characteristic you are trying to improve. Work with the coatings manufacturer to ensure system compatibility. Before applying coatings, all substrates should be clean and free of grease, oil, moisture and chemicals.
Coatings are described both by their chemical composition and appearance. All coatings are composed of a vehicle — the liquid portion of the coating and pigment which is added if the coating is opaque. The vehicle is often composed of a binder and a solvent. The binder holds the pigment together while the solvents dissolve the binder and adjust the viscosity of the coating. Coatings are further described as solvent-based and water-based. Solvent-based coatings contain organic solvents. Water-based coatings are water soluble. Clear coatings, coatings without pigments are used when you want to see the substrate; for example, you might apply a polyurethane coating to a wood gymnasium floor to protect the floor from heavy traffic and abrasion without obscuring the appearance of the wood. A semi-transparent coating on a wood substrate allows the grain of the wood to be visible but changes the color. An opaque coating completely covers the substrate, changing its natural appearance.
Dry-film thickness (d.f.t.), wet-film thickness (w.f.t.), mils (1″/1000) and inches are the units typically used to measure coatings. When comparing coatings, make sure that the units are the same on the test results since thicknesses will vary depending on the units used. Since most coatings have a recommended maximum thickness per application layer, when calculating the application time, consider the total required thickness of the system. The cost of a coating includes not only the material itself but the preparation of the substrate and the application time.
The application of coatings is affected by the environmental conditions present during installation. Sudden changes in temperature or atmospheric conditions at the time of application may negatively affect the coating and/or substrate. Always consider the application properties of the coating system. Is it easy to apply? Does it have fast-drying properties or a tolerance to moisture? Assess the environmental conditions present and the application properties of the coating. Ease of application can reduce installation time and costs.
Only select coatings that have been tested using industry standards. When selecting a coating, identify the performance standards to which the coating must meet or exceed. By using manufacturer test results of the system you are considering, it’s easy to establish a baseline standard of quality. Request test results from manufacturers for candidate coating systems to fine-tune your pre-approved coatings list.
In addition to the functional performance properties of the coating, consider the longevity of the system and life-cycle costing. What is required to maintain the finish? Is it easily cleaned? What products and processes are required and how often does the manufacturer recommend using them?
Lastly, environmental regulations specifically HAP’s (hazardous air pollutants) vary from region to region. Ensure that any coatings you are considering for your project comply with the local environmental regulations. Although there has been an attempt to streamline regulations, there are still some individual states that have their own. Requirements for VOC’s (volatile organic compounds), although stringent, are more consistent across the U.S.