High Solids Coatings

Definition - What does High Solids Coatings mean?

High solids coatings are single- or two-component coatings formulated to have higher concentrations (at least 65%) of solid components (binders, pigments and additives) than conventional coatings but still maintain satisfactory coating or application properties in spite of the lower percentage of volatile organic compounds (VOCs). They can be solvent- or water-based coatings.

High solids coatings are generally considered more environmentally friendly than conventional coatings because less solvent is emitted as it dries or cures.

Corrosionpedia explains High Solids Coatings

High solids coatings became widely used in the aerospace industry and other industries as a way to comply with the Environmental Protection Agency’s (EPA’s) emissions regulations. To address deteriorating air quality, the EPA enforces a law that limits the quantity of Volatile Organic Compounds (VOCs) or thinners/solvents emitted into the atmosphere.

Solvent-based coatings are generally ranked as a major source of harmful VOCs. While there is no requirement on the amount of solids in coating materials, higher solids content generally implies that there is lower solvent content, thus reducing VOC emissions. Paint manufacturers developed and produced low-VOC coatings in reaction to stricter environmental regulations.

High solids coatings are durable, cost-effective and less harmful to human health and the environment, but they are more expensive and require spray equipment and more skill to apply. Other disadvantages compared to conventional coatings are:

  • Higher viscosity, which causes difficulty when spraying.
  • Shorter shelf life.
  • Sensitivity to inadequate substrate cleaning.
  • Narrower "time-temperature-cure" application window.
  • More difficult to repair.

So, why don’t they just use water-based coatings?

Water-based coatings that contain very little solvents seem to be the logical solution to the problem of exceeding the VOC emission limits. However, while water is recognized as the universal solvent, it is also a key component that favors the corrosion process. This is not a problem with solvent-based coatings.

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