PAINT & POWDER
How Black is Black ? Find out using the new spectro2guide Pro from BYK-Gardner
Black is not a typical colour that arises from the absorption of a specific wavelength of visible light and the reflection of the complementary colour . A surface appears black whenever it reflects less than 1 % of light . But not all black colours are the same . Deep black coatings can also have an undertone – bluish or brownish .
A bluish undertone is often preferred for technical applications as it creates a more brilliant and darker looks .
Brown undertones are perceived as warm and are thus often used for interior applications like wood coatings .
Quantifying Blackness
For many years colour stability and harmony have been a key quality criterion for manufacturers and customers alike ... and due to its low light reflectance , black is also one of the most difficult colours to measure . To measure the deepest blacks with a reflectivity of 0.1 % or less , a new approach is required in combination with careful sample preparation to ensure reliable and reproducible quality assurance measurements with a hand-held spectrophotometer , as well as a good correlation with our visual assessment .
To determine how black is black , three specific indices are used , specified in international standard like ISO / DIS 18314-3 .
Blackness ( My ) - is a measure of the degree of blackness , directly related to reflectance without considering the coloured undertone .
Jetness ( Mc ) - is the colour depending blackness value - a higher Mc value indicates a deeper black
Undertone ( dM ) - describes the amount of blue shade in case of positive values and the amount of brown shades in case of negative values
Black . Blacker . Blackest
Measurement of the deepest black colours places high demands on a measurement instrument and pushes the technical performance of a handheld spectrophotometer to the utmost limit . The basis for the excellent performance of the spectro2guide Pro is the use of high-power LEDs as light source , which , thanks to the BYK-specific production control process , provide an exceptional short-term as well as long-term stability and ensure an absolutely homogeneous illumination of the measuring spot . To master the “ signal to noise ratio ”, highest precision electronic and optical components are combined with a special calibration and operation mode for measurement of black colours : LED lamps are powered with more energy resulting in a higher light intensity and the illumination time is extended . In this so called Jetness-mode colours with low black values cannot be measured . The user is asked to remeasure the sample in the “ regular ” measurement mode and the so-called G-values ( Grayness values ) will be shown in lieu of M-values . The Jetness indices ( M-values and G-values ) are defined in DIN ISO 18314-3 .
The technical performance of the spectro2guide Pro is outstanding even on deep black samples with a blackness value My value close to 400 . Furthermore , the spectro2guide family consisting of spectro2go , spectro2guide and spectro2guide Pro is the only spectrophotometer on the market that is capable of measuring colour and gloss as well as predicting the long-term color stability of a sample . The lightfastness is analysed by the combination of a spectrophotometer with a fluorimeter . The spectro2guide Pro opens completely new perspectives to control colour harmony and guarantee colour stability - no matter what colour and how deep the black may be .
Introducing the highest accuracy 45 / 0 spectrophotometer for the darkest blacks – spectro2guide Pro 45 / 0
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38 SEPTEMBER 2021 twitter : @ surfaceworldmag