Rag paper: Papers with a complete or partial content of cotton fibers.
Ragged Left: The term given to right-justified type that is uneven on the left.
Ragged Right: The term given to left-justified type that is uneven on the right.
Railroad Board: A thick, coated paper used for signs; usually waterproof.
Readers Pairs: Two consecutive pages as they appear in printed piece.
Ream: 500 sheets of paper.
Recto: The odd numbered pages (right hand side) of books.
Red Lake "C": A common pigment for paste and liquid red inks.
Reducer: Any substance that softens and reduces the tack of ink.
Reel: The master roll of paper as it comes off the papermaking machine. It is in its original width and is then cut into smaller rolls.
Register: The arrangement of two or more images in exact alignment with each other.
Register Marks: Any crossmarks or other symbols used on layout to assure proper registration.
Right Angle Fold: A term that denotes folds that are 90 degrees to each other.
Roll To Roll: A web press printing process where the roll of paper is printed and stored on a roll to be shipped.
Rub Proof: That stage of printed ink where the maximum dryness is achieved, and the ink will not smudge.
Rubine: A pigment somewhat redder than true magenta.
Run-Around: A term given to copy that accommodates the lines of a picture or other image or copy.
Runability: A term used to describe how well a paper runs on a printing press.
Running Head: A title at the top of a page that appears on all pages of a book or chapter of a book.