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CIE L*a*b*




Based on the data and contract proofs standardized by us in colour space FOGRA39L (ISO Coated v2), the whiteness is defined with the value L* 93 a* 0 b* -3 (according to the characterization for PC1 of the FOGRA39L) for laminated prints (measurement condition: M0, black backing, D50/2°, geometry 45°/0° or 0°/45°).



Guidelines for colour measurements

The measuring instruments and reference backings must comply with ISO 13655: measuring geometry 0°/45° or 45°/0°; Colourime-try for the 2° observer; Standard illuminant D50 (5000 K); CIELAB colour metrics (L*, a*, b*); matt white backing under the sample (ceramic, plastic, cardboard or 3 proof substrates) gloss ISO 8254-1 (75 °) <40, free of optical brighteners, chroma C *ab from <3.0 or better <2.4, from ISO 13655:2017 the white spectral values lead to brightness L* between 91.2 and 96.4); for process control un-der production conditions a matt black backing under the sample with a colour density of approx. 1.5.

To maximize repeatability in foil measurement applications, spec-tral densitometers / spectrophotometers must be aligned so that they are exactly with the machine direction of the foil (90° or 180°) for all measurements.