Preparing Your Files for Print – Prepress Basics
The first challenge to preparing your files to be printed is understanding the different terms used in commercial printing. This post will educate you on those terms and explain how to prepare your files. Some might be a little complicated for the average person (i.e. trapping), but if you are able to pick up on these procedures, you can save yourself lots of money in prepress charges.
What are Commercial Printer’s Marks?
The following diagram explains the different marks used in commercial printing:
What is Bleed?
When you are having something printed and you want the image to go off the edge of the page, you need what is called bleed. Whether on a digital press or a printing press, bleed is necessary. Bleed is an area of the image or color in your art that you make at least 1/8″ (.125″) bigger on each side. What that does is ensure that when the paper is trimmed down to its final size, there will be no area showing that is not covered with the printed image.
Image Resolution for Commercial Printing
Images used in commercial printing need to be a minimum of 300dpi or higher. A photo needs to be taken at that resolution, or the art needs to be created from the beginning at that resolution. You cannot take a lower resolution image and tell it to be 300dpi after the fact. If the resolution was not there from the start, it can’t be added.
Images for the web are created at 72dpi which is the resolution of your screen.
What is Trapping and Do I Need It?
When you are printing more than one color at a time on a commercial press, the areas where the two colors meet need to register perfectly, or you get a gap where there is no ink. To fix this problem, we do what is called “Trapping.” It is a way to spread one of the ink colors further out then normal so that if the press doesn’t register perfectly, there is some ink printing to cover the gap.
If you are having something printed on a digital machine, you don’t need to worry about trapping. Most of what we do at Daubenmire Printing Innovations is done digitally, but envelopes and some forms and letterhead are still printed on presses. If your job is 2 colors or more and will be printed on a press, trapping is something you need to consider.
Trapping is very difficult to set without the right software, so it might be best to allow Daubenmire Printing Innovations to set your trapping. If you are creating your job in Adobe Illustrator or InDesign and would like to set your own trapping, contact me (Jennifer) at 513-425-7223 and I would be happy to walk you through it.