1.1 This part of ISO 105 specifies a method intended for quantifying the whiteness and tint of textiles,
including fluorescent materials.
1.2 Whiteness as measured by this test method is an indication of how white the textile appears to an
average viewer. Tint, if other than zero, is an indication of a reddish or greenish hue having shifted away
from a bluish (neutral) hue with a dominant wavelength of 466 nm. The formulae for calculation of
whiteness and tint are those recommended by the CIE1).
1.3 Because reflectance is affected by the nature of the surface of the textile, comparisons can be made
only between specimens of the same type of textile.
1.4 The application of the formulae is restricted to specimens that are called "white" commercially, that do
not differ much in colour and fluorescence and that are measured on the same instrument at nearly the same
time. Within these restrictions, the formulae provide relative, but not absolute, evaluations of whiteness that
are adequate for commercial use when employing measuring instruments having suitable modern and
commercially available capabilities.
1.5 Many impurities in textiles absorb short wavelength light, resulting in a yellowish appearance to
observers. Therefore, a measurement of whiteness may be an indication of the degree to which a textile is
free from impurities.
1.6 The effect of blueing components or fluorescent whitening agents (FWAs) on the whiteness of textiles
may also be determined using the whiteness measurement.