1.1 These test methods deal with the measurement of optical properties important to automatic equipment used by the United States Postal Service, such as optical character recognition (OCR) readers and barcode readers. These test methods can be used to examine finished mailpieces bearing address information, as well as the unconverted materials intended to be subsequently used in mailpiece construction. These test methods are limited to the use of a single instrument, the U.S. Postal Service Envelope Reflectance Meter Model 2 (ERM-2), designed for use with mailpieces and materials intended for mailpiece construction such as paper and paper-like synthetics and inks.

1.2 These test methods cover examination of small areas, measuring 0.152 by 0.254 mm (0.006 by 0.010 in.). This enables measurement of the reflectance characteristics of regions as small as the inked portion of a single printed character or a single bar in a barcode pattern.

1.3 These test methods deal with the measurement of four different optical properties important to automatic mail handling, as follows:

1.3.1 Background Reflectance (see 11.1)—These test methods cover the determination of the relative reflectance factor of small areas of a specimen that do not contain printing or apparent show-through of printing, and so are representative of the base material.

1.3.2 Print Reflectance Difference and Print Contrast Ratio (see 11.2)—These test methods characterize the difference in reflectance between the envelope material and the characters printed upon the envelope with ink.

1.3.3 Print Show Through (see 11.3)—These test methods characterize the difference in reflectance between the envelope material backed with an unprinted insert and the envelope material examined in a region where it covers a printed character on the insert or a character printed on the back side of the envelope material itself.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.