The importance of regular calibration of reflectometers cannot be overstated. It is an essential prerequisite for accurate and reproducible measurements of the optical properties of pulp and paper products. FPInnovations produces optical reference standards in an Elrepho master instrument from Lorentzen & Wettre.
FPInnovations – Optics Laboratory has over 40 years of experience in the field of optical calibration and is one of five ISO-Authorized laboratories worldwide for issuing IR3 Reference Standards for measuring optical properties of pulp, paper and board. Paprican provides consultation and diagnostic materials for resolving colorimetric problems, actively pursue technical innovations in this field, and contribute to the development of ISO Standards.
ISO optical calibration hierarchy
A strict calibration hierarchy is specified in all ISO Standards that deal with the measurement of the optical properties of pulp, paper, and board. According to this hierarchy, an ISO-Standardizing Laboratory uses a level 1 (IR1) Standard Material - based on a hypothetical perfectly reflecting diffuser - to prepare level 2 Standard Materials (IR2) for distribution to ISO-Authorized laboratories. The ISO-Authorized laboratories then produce Level 3 (IR3) Reference Standards that are issued to the end-users. Various laboratories use IR3 Standards to calibrate the working standards that are provided with their instruments.
FPInnovations standards produced on an Elrepho
All of the ISO Standards on optical properties, including those for measuring brightness, indoor (C illuminant) and outdoor (D65 illuminant) whiteness, color, opacity, and absorption and scattering coefficients, specify the use of IR3 Reference Standards, as described in ISO 2469: Measurement of diffuse reflectance factor. In addition the scope of the ISO brightness Standard (ISO 2470) has been expanded to include IR3 fluorescent Reference Standards.
FPInnovations' IR3 Standards are produced on an Elrepho instrument according to ISO Standards 2469, 2470 and 11475, and are traceable to the National Research Council (NRC) Standardizing Laboratory in Canada. They are provided in a package comprising two types of paper tabs, for reflectance calibration, and UV adjustment for fluorescence measurement, respectively, and include a calibration certificate. The non-fluorescent Reference Standard is a cotton-based paper, whereas the fluorescent Reference Standard is a white wood-free fluorescent paper.
For the non-fluorescent Reference Standard, spectral reflectance factors are provided over an extended wavelength range from 360 to 700 nm at 10 nm and 20 nm bandwidth. ISO Brightness, Tristimulus values Rx, Ry, Rz, and their corresponding X, Y, and Z values are also given for C/2o illumination. For the fluorescent Reference Standard, ISO Brightness (C/2o) and CIE Whiteness (D65/10o) values are included in the certificate. The data are also available electronically or on CD for direct transfer onto the Elrepho.
Regular, traceable calibration is a fundamental requirement
Reliable and consistent data are key requirements for better control of process conditions, and reduced product variability. In particular, effective use of on-line sensors for measuring optical properties of paper relies on the use of off-line calibration. Most importantly, properly calibrated instruments can prevent disagreement between papermakers and their customers, and avoid incurring excessive and unnecessary costs.
Retired Program Manager at FPInnovations
FPInnovations produces optical reference standars in Elrepho master instrument from Lorentzen & Wettre.
FPInnovations' IR3 standards are produced on an Elrepho instrument according to ISO standard 2469, 2470, and 11475.