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Monday, July 27, 2015

TAPPI Brightness Calibration History

The Paper titled “Instrumentation in Brightness Grading” by Myrl  N. Davis of Kimberly Clark, was published in  Paper Trade Journal in  1935. This paper  provides a good deal of information about the formative days of the TAPPI/GE  Brightness tester and calibration system.

In the two or three years preceding November, 1933, Davis and his associates spent most of their time using and attempting to interpret and apply the data obtained using instruments for measuring the color of “white” book papers. They discovered that when two samples of paper were compared visually and by measured reflectances of various colors of light, it was found almost invariably that the visually “brighter” of the two samples reflected the higher percentage of blue light.

The first recorded attempts to find a correlation between test results and the cost of several grades of white paper were  made in November 1933. The reflectance of blue light and goodness of formation were found to be the only measured properties which were even closely associated with the cost of the papers tested. Both properties were selected by the Grading Committee of Book Paper Manufacturers Association as physical qualities upon which to base a system of paper grading.

The term “brightness test” was immediately applied to the measurement of the reflectance of blue light and the instrument for making these tests came to be known as the “brightness tester” before anyone had more than a vague idea of what the instrument would be like.

Davis, et.al. came to the conclusion, based on experience with two dissimilar instruments, that an instrument suitable for making the brightness test and capable of the necessary accuracy could be built. They established the requirements for such an instrument, and when the design was offered by the General Electric Company, they gave their approval.

The decision to attempt the use of the brightness test in the grading of uncoated book papers was made on November 16, 1933. The first model of the General Electric Reflectance Meter was delivered to the Institute of Paper Chemistry on December 21. On January 16, 1934 the  IPC  was able, not without some misgivings, to present to the Book Paper Grading Committee a complete set of brightness data on all samples of uncoated book papers presented for test. From this data, the official brightness values for grade separation were adopted and the brightness scale was, thereby, officially fixed.

At that point, the work of calibrating, distributing and servicing brightness testers and the responsibility for maintaining the brightness scale in its proper position was assumed by the Institute of Paper Chemistry. Subseqently, in September, 1934 a bimonthly calibration service was begun by IPC.

The above was all taken from the paper “Instrumentation in Brightness Grading” by Myrl N. Davis.

Here are some other facts:

In 1955, GE turned over the manufacture of the Brightness Tester to the Martin Sweets Company.

In 1973, Martin Sweets Co. turned the manufacture of the Brightness Tester over to Diano Corp.

In 1978, Diano Corp turned the manufacture of the Brightness Tester over to Technidyne Corporation.

In 1982 Technidyne began shipping instruments directly to paper industry customers, rather than shipping all instruments to the Institute of Paper Chemistry.

In 1989, Technidyne established its standardization laboratory and began shipping calibration standards to the Pulp and Paper industry.

In 1998, Technidyne became an ISO Authorized Laboratory.