TAPPI T452

Your guide to TAPPI T452

TAPPI T452 is the industry standard method for testing the brightness of white, near-white, and naturally colored pulp, paper, and paperboard. It offers an easy way for you to determine one of the most important optical qualities of your paper packaging and products. Read on for everything you need to know about TAPPI T452.

What is paper brightness?

In the industry, brightness is commonly used as the name for the numerical value of the reflectance factor of a sample with respect to blue light of specific spectral and geometric characteristics.

Are brightness and whiteness the same thing when it comes to paper and board? Not exactly, while they’re related optically they are not the same. In fact, there is no known mathematical relationship between the two values. Find out more in our guide to the relationship between brightness and whiteness.

The TAPPI T452 test method

To measure papers, pulps and boards using the TAPPI T452 method you need an instrument employing 45° illumination and 0° viewing geometry with the illuminating and viewing beams adjusted so that translucent materials are evaluated on an arbitrary but specific scale. The cone of light (see A.3.2 and A.3.5) used by this method is wider than that specified for the CIE Standard 45/0 geometry.

It uses blue-light reflectance to determine the optical brightness of the sample. The higher the blue-light reflectance, the whiter the products will generally appear. TAPPI T452 was originally developed to determine the amount of bleaching that has taken place in the manufacture of pulp and has become a more widespread standard testing method for brightness.

For an automated and accurate testing process for TAPPI T452 brightness, our recommended products include the PROFILE/Plus TAPPI Brightness machine, which offers top and/or bottom brightness and fluorescence measurements.

What can TAPPI T452 be used on?

TAPPI T452 can be used to determine the brightness of papers and board made from naturally-colored pulps and is suitable for optically brightened pulp and paper. It is also suitable for paper or paperboard containing added coloring matter, like yellow or green dyes, which appreciably absorbs light in that part of the spectrum extending from about 400 to 500 nm.

However, it is not suitable for colored papers. For meaningful results for colored paper, they must be measured either spectrophotometrically or colorimetrically.

Meeting testing standards with Industrial Physics

Staying up to date with industry testing standards is essential for a wide range of industries and at Industrial Physics, one of our key aims is helping you achieve exactly that. We look both backwards and forwards when it comes to designing testing solutions and our specialist testing brand Technidyne has been at the forefront of paper and pulp testing standards for decades. Browse the Technidyne range for more paper testing solutions.