The methods for creating energy efficient cool gray building coatings—Part I: Preparation from white and black pigments

We describe the method for creating nominally cool gray coatings by mixing titanium dioxide rutile and black pigments that include chromite iron nickel black, manganese ferrite black spinel, perylene black and dioxazine purple. Although the solar reflectance of the gray coatings prepared by adding chromite iron nickel black and manganese ferrite black spinel pastes separately into a white coating are higher than that of the standard gray coating of colors of similarly lightness with the mixtures of carbon black and titanium dioxide rutile, they are actually not qualified cool gray coatings. The light gray coatings colored with a mixture of perylene black and titanium dioxide rutile are eligible cool gray coatings with a green shade. The gray coatings produced by mixing titanium dioxide rutile and dioxazine purple and chrome titanium yellow are also real cool coatings with a violet shade. •The coatings colored with Cr–Fe black and TiO2 rutile are not cool gray coatings.•The coatings colored with Mn–Fe black and TiO2 rutile are not cool gray coatings.•The coatings colored with perylene black and TiO2 rutile are real cool gray coatings.•The coatings colored with dioxazine purple and TiO2 rutile are cool gray coatings.