July 2005, V4#7: Production Thursday, Jan 29 2009 

Paper opacity is the lack of transparency that allows a sheet to conceal print on the opposite side.  weight, brightness, type of fiber and filler in testing can all greatly influence opacity.  Reflectance of paper is measured when backed successfully by a white body and a black body.  The ratio of these two measurements determines the opacity reading.  Typical opacity of 50# white offset is 88-90; 20# business paper is 84-88.  A quick and very basic “home” test is to print something large and black (black and white clip art and or various sized of bolded text) on a sheet of paper, place a blank sheet of the paper to be tested over this printed sheet.  Any print that happens to show through, will show a bit more if actually printed on the currently black paper.  For book printing, take your darkest page and try this test.  Many manuscript designers will change their manuscript elements to decrease the opacity needed for a nice book rather than pay the difference for higher opacity.


June 2005, V4#6: Define Wednesday, Jan 28 2009 

Against the Grain: Folding, scoring, binding, or printing at right angles to the alignment of the fibers of the paper.

May 2005, V4#5: Production Wednesday, Jan 28 2009 

Paper Grain Direction:  All papers have a grain direction.  When the grain runs along the longest dimension of the sheet, the paper is “long grain”.  Grain is seldom a factor in offset printing, however it is a major consideration in binding.  Binderies prefer long grain since paper offers the least resistance in the same direction as most fibers in a sheet.  Also, pages in books tend to lie flat better when they are made with, rather than against the grain.  For saddle stitched books, a stronger book is produced with long grain, due to the fold being across the grain, but it doesn’t lay as flat.  Short grain paper is has difficulty maintaining dimensional stability and may result in more book problems such as wrinkled pages, etc.

May 2005, V4#5: Define Wednesday, Jan 28 2009 

Paper Grain: The direction fibers within paper generally lie, corresponding to the direction of their flow on the papermaking machine.