October 12, 2018
When designing books there are many small details to consider to make the end product look professional. During the design phase elements may appear to be positioned appropriately while looking at the computer screen but factors such as how well will the book open and where glue will be applied become factors in the final book reading experience.
Glue strips at the beginning and the end of the book are required to hold the cover and the interior pages together but are not always something that is considered at the design stage. There is no visual indication in InDesign that there will be a glue strip on the first and last pages stealing away valuable real estate from the page content. For many books this does not pose a problem because the title page often has generous margins that can accommodate losing a little margin without looking off centre. For pages with images that fill the screen it is more obvious that losing image will be a problem. When there is no background image on the page it is easy to overlook the glue strip as a factor. With a small title that has generous margins the title being slightly off centre is hardly discernible. On a wide title the mismatched margins become more obvious and become something that would be worth compensating for. On a 6 x 9 inch book this is a matter of centring on a 5.75 inch width rather than the full six inches.
When gluing the endsheet of a hard cover or the soft cover to the first page of the book there will be 0.25 inches along the spine edge of the page that will be hidden by glue. The actual area reserved for glue is 0.1875 inches but the full area affected is 0.25 inches. This is a factor for centering and also for full page images.
A design that I have been seeing with more frequency recently is the placement of images that flow from the inside cover, across the glue strip and over to the first page of the book. On books where the inside cover is a solid wash or there is no detail in the glue strip area, this is a simple matter to prepare. When the picture selected has detail that extends across the glue strip the image needs to be split carefully so the image will line up again after the cover is glued and assembled with the interior pages.
A good example of this challenge is placing an image of a tree across the inside cover and first page. For the horizontal branches the total of a half inch lost is hardly noticeable other than the fact that the limbs are a little shorter. When branches extend across the glue strip at an angle the image loss becomes easily seen as the limbs are cut off or are disjointed.
The method I use to prepare the files is to first place the image in the desired location on page one of the book. After the image is placed, crop the image at the spine to lose 0.25 inches. This will account for the glue strip at the spine. Next make a duplicate of the image that is right on top of the original. Open the left side of the top image so it extends across the glue strip and into the pasteboard. Now grab the right side of the newly extended image and close the box until it is cropped enough to align with the left edge of the page one image.
In the end the goal is to have two image boxes that contain a continuous image with the split occurring 0.25 inches from the edge of the left side of page one. The image on the left that is extending into the pasteboard is the image to use for the inside front cover. Cut this image out of page one and place it into the inside cover file. Position the right edge of the image 0.25 inches from the left side of the spine to allow for the glue strip area. Now both the first page in the book and the inside cover contain half the image with a gap for the glue strip.
One other adjustment is needed to include a slight overlap to make certain that the blank glue strip area does not show even if the cover is pried wide open. The picture box on both the first page and the inside cover are opened 0.0625 inches toward the spine. This creates a repeated image area of 0.0625 inches on each side leaving a white glue strip area of 0.1875 inches. When working with the last page of the book these same methods can be used to account for the glue strip. Make sure that no text will be lost on the last page or the endsheet after the glue strip is
added. The glue strip will be on the right side of the last page, so use the reverse method when cropping and splitting images to cross the glue strip.
The same method is used for a hard cover but rather than using the left side of the image for the inside front cover, the left half of the image is used as page F4 of the endsheet. Keep in mind that even when the transition of images between the two pieces of the book is well executed, differences in paper stock will change the look of the colour on each panel. Use these strategies to ensure that your book has images that transition successfully across the glue strip.