Standard GB/T 23981-2009 "Paints and varnish - tristimulus values and reflectance method for the determination of Paints contrast ratio", this standard aims to specify the method for determining the white or light Paints Coating contrast ratio (hiding power). The standard evaluates the ability of the paint to eliminate the substrate Color by using the tristimulus values method or the reflectance method. In the method, the reflectance of the coating on the black and white substrates is measured and used to calculate the contrast ratio. The lower the contrast ratio, the stronger the covering ability of the paint, that is, the more effectively it can eliminate the Color of the substrate. This standard applies to Spreader's paints on black and white card paper or colorless transparent polyester film, and is designed to evaluate the performance of paints to meet specific needs.
So do you know the difference between the concepts of reflectance, hiding ratio and contrast ratio in the field of Coating?
Reflectance
Reflectance refers to the reflection ability of Coating on black and white substrates. In some standards, reflectance is calculated by measuring the reflectance of Coating on black and white substrates. The reflectance (RB) of Coating on black substrates is divided by the reflectance (Rw) on white substrates to obtain the contrast ratio, which is used to indicate the degree of reflection of Coating on light. The higher the reflectance, the stronger the covering ability of Coating, that is, the lower the contrast ratio, the more Coating can eliminate the Color of the substrate.
Hiding ratio
In some standards, the hiding ratio, also known as the contrast ratio, refers to the ability of the coating to eliminate the substrate Color. The hiding ratio (or contrast ratio) is measured by comparing the reflectance of the same coating on black and white substrates. The lower the contrast ratio, the better the Coating covering ability, as it is able to remove the substrate Color more effectively. In other words, the hiding ratio (or contrast ratio) reflects the degree to which the Coating covers the substrate Color.
Contrast ratio
In some standards, the contrast ratio is calculated by comparing the reflectance of the coating on a black and white substrate. It indicates the ability of the coating to eliminate the substrate Color. The lower the contrast ratio, the stronger the covering ability of the coating, because it more effectively eliminates the substrate Color, making the Coating Color more visible.
Therefore, in this standard, the hiding ratio and contrast ratio are actually different descriptions of the same concept, used to evaluate the ability of the coating to cover the substrate Color, while the reflectance is the basis for the contrast ratio calculation.