Plates is a word with many meanings.  It takes till definition 17b for the Oxford English Dictionary to get round to the meaning “insert”: “An impression from a printing plate, an engraving, an illustration; (now usually) a photograph or picture occupying a whole page in a book, often printed on better quality paper than the other pages, and not forming part of the main page sequence.”  To use the word plate in this sense has a slightly old-fashined ring to it, but publishers still often use it in text call-outs or in announcing in advertising copy that the book contains an insert.

There are three ways in which a group of illustrations may be handled.

  1. an insert printed on different paper (coated paper usually) from the rest of the book
  2. a photo gallery, which is similar to No. 1 except that it is printed on text paper
  3. a group of illustrations printed on text paper included in the pagination of the book.

The reason why plates are printed on coated paper as a separate component of the book is almost totally based on convention.  When books were printed by letterpress, or indeed in the early days of offset, a halftone printed along with the text on the same paper, would tend to be of problematic quality.  You didn’t want the presence of a few halftones to force you into printing the entire book on coated paper (which is much more expensive) so the practice developed of gathering the halftones together and printing them separately on coated paper.  This separate insert would then be gathered at the same time as the rest of the book and bound together with the text.  This practice has now (like so many things in book making) developed into a convention, and is almost expected by the market.  So when we do a history trade book we will print the halftones as an insert, not because we couldn’t print them perfectly satisfactorily on the text sheet, but because for that sort of book we think the readers expect to see an insert, and perceive it as adding value.  There is nothing “wrong” with this convention, and it does become almost an imperative when the illustrations are in color.  But inserts are an inconvenience.

I can accept (just about) that the superior ink hold-out of a coated sheet will give you a better reproduction of a medical illustration, and that this could constitute a reason for having an insert.  However when you are printing pictures of the subject of a biography and her family, or a bunch of engravings relating to the Revolution, the material just does not demand coated paper.  What demands the coated paper is market expectation.  I am not under any illusion that I can change this, but I do like to be clear about which parts of our job are rational and which emotionally based.

When we are originating the book, we cannot be sure where an insert will fall – it either has to go between signatures, or (more expensively) in the middle of a signature, and until we have finished typesetting we cannot know where the signature breaks will fall.  As we do not know what pages it will fall between, we do not assign page numbers to the insert.  Thus if a 4-page insert is bound between pages 192 and 193, the pagination, if you were going through the book counting, will go 192, 192A, 192B, 192C, 192D, 193, 194 etc.  When we submit files to the printer we send the Interior as one PDF and the Insert as a second PDF.  This is justified by the fact that the insert will indeed be printed on a different press from the rest of the book, although not probably, as used often to be the case, at a different location.

Inserts, because they require special paper and separate handling in manufacturing, cost more.  Because of this, over time thrifty publishers came up with the compromise of printing some “inserts” on the text paper.  This we often refer to as “a photo gallery”.  A photo gallery will resemble an insert in every respect, except for the paper on which it is printed.  Like an insert it is not paginated.  One disadvantage of a photo gallery is that it is difficult for the reader to locate.  An insert is obvious because the contrast between the coated paper and the text paper jumps out at you.  From a file archiving point of view, the fact that the insert file is separate from the Interior file leads to the potential for recovery from the archive of an incomplete book.  Where there’s a photo gallery not an insert, treating this as a separate file, which all too often happens, is really crazy.  If the gallery is paginated in with the text there is at least some possibility of this being noticed, but most often photo galleries get no page numbers by result of their descent from an insert.  Omitting the gallery from the file is essentially no different from omitting chapter two.  Please don’t do it.