Drawdown card
Encyclopedia
Drawdown cards are used for testing paint
s and coating
s through wet film preparation.
Black and white cards are used to measure both opacity
and contrast ratio
. By measuring reflectance values of both parts of the card one can gain a quantitative opacity value of a paint sample.
Paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
s and coating
Coating
Coating is a covering that is applied to the surface of an object, usually referred to as the substrate. In many cases coatings are applied to improve surface properties of the substrate, such as appearance, adhesion, wetability, corrosion resistance, wear resistance, and scratch resistance...
s through wet film preparation.
Black and white cards are used to measure both opacity
Opacity (optics)
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc...
and contrast ratio
Contrast ratio
The contrast ratio is a property of a display system, defined as the ratio of the luminance of the brightest color to that of the darkest color that the system is capable of producing...
. By measuring reflectance values of both parts of the card one can gain a quantitative opacity value of a paint sample.