The basics of Airless Spraying – Coatings
Architectural coatings are primarily decorative coatings used to coat anything from homes to commercial and industrial buildings.
Protective coatings are primarily corrosion control coatings used to coat anything from bridges to water towers, preserving concrete and steel. Often these coatings are two-component materials.
The majority of coatings are sold at paint stores, generally to professional painting contractors.
Virtually every coating contains four basic components:
• Binder, Resin, or Polymer—holds together the other components prior to application and forms a protective film on the surface (the
surface is also called a substrate) to which the coating is applied. Binders can be oils, varnishes and proteins.
• Pigment—fine solid particles that hide the surface providing decorative colors and sometimes corrosion resistance. Raw umber, a type of iron ore, is used extensively as a pigment and is olive green in color.
• Solvent—helps the flow of the coating material and aids in application. For example, water is a solvent for sugar. However, in many coating formulations, a chemical referred to as a solvent, may not be dissolving anything, but simply diluting or thinning the formulation.
• Additives—in general, manufacturers put additives into coatings for one or more reasons, including aiding in manufacturing, enhancing application characteristics, or improving the properties of the coating once it is cured. For example, some additives help prevent mildew from forming once the coating has cured.
Paints and other coatings are rated by the volume of solids they contain. While virtually everyone in the architectural coatings industry refers to the “low,” “medium,” and “high” solid content of coatings, there are no set amounts or limits placed on these categories. A typical set of values for coatings is:
• Low Solids = 20-30% solids
• Medium Solids = 30-50% solids
• High Solids = Up to 100% solids