Mini-Encyclopedia of Papermaking Wet-End Chemistry
Part Two: Definitions and Concepts

Metamerism

You know you have an instance of metamerism if two paper sheets look identical under one set of lighting conditions, but they appear to have a different shade from each other under a different illuminant. The major causes of metamerism problems are (a) poor selection of dyes when the same grade is made on different paper machines, (b) different effective levels of fluorescent whitening agents, especially in white grades, and (c) attempting to make the same grade with very different types of fiber furnish. Metamerism in color paper grades usually can be avoided by making sure that the red, yellow, and blue dyes each have a similar hue to the dye used when making the standard that was approved by the customer.

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This page is maintained by Martin hubbe, Associate Professor of Wood and Paper Science, NC State University, m_hubbe@ncsu.edu .