Basic Paper Primer

Paper  weight is based on the basic size of a given paper as determined by a given mill.  For this reason, many weight notations one finds has at least 2 separate numbers.  This does not necessarily mean the weight fluctuates between the two.  Generally with printers and suppliers is not a range, but a definition from more than one source and may include more than one grade of paper (bond, text, etc.).  A 50/60# paper is ordered as 50# and as 60#.  However, when put through standardized testing, it is found that each sheet carries the same weight. All specifics supplied If in doubt, check with the business presenting the number information for formal explanation.  Gregath paper suppliers do recognize the standard variation in basis weight of + or – 5% as acceptable by industry standards.

Paper brightness affects the legibility and contrast of printing.  The brightness test measures the reluctance of paper under strict optimal conditions and related it to a white standard (Magnesium Oxide).  The test is mainly applicable to white paper grades.  Basic offset grades are usually in the 80% brightness range.  Aesthetic importance may also be given to the brighter papers.  However, if archival quality is a focus, one must be certain that it is not traded for the brightness.  White papers with 90+ brightness sometimes actually have a blue or colored cast due to additives. 

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