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.