In the print industry, bleed is a term that describes the printed area that extends past the borders of the finished product. The sole purpose of this extra printed area is to serve as a buffer for imperfections that occur during the production process. Bleeds are only required for designs that have printed elements that reach the edge of the media.
When producing printed goods, there are accepted industry tolerances for accuracy with respect to printing and cutting. During production, the media (typically large sheets of paper) can shift and rotate slightly. This can result in small inaccuracies with the positioning of the ink/toner on the paper. Due to these movements, certain designs are more susceptible to visible production flaws. An example would be a design where the entire surface is covered in ink from edge to edge. Another example would be a business card design that has any printed elements that touch the edge of the media. For the latter, this element could simply be a line that extends from the top of the card to the bottom, which runs from edge to edge. For either of these examples, printing without bleeds would make a small misalignment easy to notice because a small amount of space near the edge of the media would not have any ink.
A more detailed explanation of how bleeds work could involve a business card that has its entire front surface printed a solid color, possibly black. In this example, the black business cards actually start as a few large sheets of white paper. Multiple business cards (3.5” x 2”) are then printed onto each sheet of paper. At this point the sheets of paper would have many small rectangles printed on them. These rectangles are actually the business cards themselves before they’ve been cut out of the larger sheets. After the 3.5” x 2” business cards have been printed onto the larger sheets of paper, they are cut out, resulting in the finished product. In this example, there were no bleeds on the business cards, which means the rectangles (business cards) referenced above were exactly 3.5” x 2” as specified in the design. Since some of the sheets may have shifted and rotated slightly during the production process, attempting to cut out the rectangles precisely would not be possible. As the cutting blade slices through the large sheets of paper, the cutter assumes that those rectangles are in a precise location. Since the paper may have moved by 1mm, the resulting cuts will be off by 1mm. On a design like this one, a 1mm inaccuracy would leave a portion of the business card without ink. Since the desired business card had a black front surface, a 1mm sliver of white would be very visible.
Building off of the example above in our business card bleed guide, bleeds provide a way to compensate for inaccuracies. If everything else remained the same as stated above, but an extra ⅛” of black was added to all sides, the surface area would increase to 3.625” x 2.125”. This rectangle is a larger target for the cutter to cut. With a larger rectangle, a 1mm inaccuracy would not leave any part of the surface without ink. Even though the cutter/printer may have been slightly off target, the resulting business cards still have the desired edge to edge ink coverage. The main idea of this concept is to extend the printed areas for certain designs to compensate for movement and misalignments. By extending these elements, the cutting target has been enlarged, making it easier to target. A larger target is easier to hit, and also allows for slight inconsistency without compromising the overall design.
If a design doesn’t have any elements that touch the edge of the media, bleeds are not required. The same inconsistencies and tolerances still occur during production, but the finished product won’t reveal imperfections as easily as designs that have printed elements that reach to the edge of the media.