What do "bleed," "trim size," and "active area really mean?

The trim size is the actual size of the magazine you hold in your hands. To make properly square with all the pages lined up with one another, it is printed somewhat larger than this finished size, then each magazine is trimmed down to the exact trim size. Because no machine is perfect, ads must be printed a bit larger than the trim size so they can stretch from edge to edge without any white paper showing. This larger printed area is the bleed size (because the full-page image bleeds off the page). When designing your ad, you must assume that all of the space in the area between the trim size and the bleed size will be cut off. The extra printing for the bleed size is there just in case the trim is a bit off so no white of the paper shows on your full page image. 

You should never extend borders or any part of your ad you expect people to see to the edge of the trim size. Because of manufacturing tolerances, it might be cut off. To possible trimming and be sure the full contents of your full-page ad will be seen, all words and lines should be kept within the active area. 

Borders and text outside the active area result in a trim violation which will cause the page to be rejected by our printer. That is a bad thing. The page must be recomposed to eliminate the trim violation. The costs involved in the rejection and the repair to the ad will be charged to your account. That is a very bad thing.

So why do some ads have borders outside the active area? Because the printer won't call a trim violation until the offense is within a quarter-inch of the edge of the trim size. That means you can push out a bit beyond the trim size--at least on the back cover. On inside pages, however, you can count on half an inch at one side edge or the other (depending on whether the ad runs on an odd- or even-numbered page) getting lost down in the gutter. If you stay within the "active area" specs, you never have to worry about losing text in the gutter. But you can push your luck and extend your ad outside the active page area. Be aware that if you do so, you are apt to lose readability and artisitic integrity in a tumble down into the gutter. 

Why should I worry about Postscript 3?

Our printer burns plates using a PostScript level 3 RIP (Raster Image Processor). That is the most up-to-date version of PostScript from Adobe, and it allows for the most accurate production of pages and makes available to you the most features in composition. Unfortunately, PostScript level 3 differs from the PostScript level 2 used by many printers and graphic programs for proofing ads, so some ads can look a bit different in print if you don't use the latest version of PostScript for saving, previewing, and proofing them. 

The biggest problem we have encountered is with transparency in knock-outs and overprinting. When you reverse type over a colored background or put an image effect such as a drop shadow over a background, when you do not properly knock-out the background, the effects may appear different from your intentions. Reverse type may disappear or images my blot out the background. Avoid problems. Proof using a PostScript level 3 proofing system and printer. 

Adobe has a guide to handling transparency and avoiding these problems available by clicking here.

Why are all blacks not the same?

Commercial printing uses a four-color process based on four ink colors: cyan, magenta, yellow, and black, usually abbreviated CMYK. Computers generate images using three primary colors: red, green, and blue, usually abbreviated RGB. The translation between these two color spaces (as engineers call them) is fraught with difficulties. Black is the most problematic. 

There are two blacks in CMYK printing. Ordinary black uses only black ink (the K of CMYK). Built or process black uses all four ink colors to create a deeper, more intense black. The two blacks look discernibly different in print but on computer screens they look identical. If some of the blacks in your ad are ordinary black and some are process black, you will see the difference in print--and it won't look good. Check your blacks before you submit your ad.

Adobe offers a complete guide to mastering color using their software, which includes a chapter about blacks. It is available by clicking here.