The Spec Sheet
The first thing you should do is get a hold of the specification
sheet from whoever will be printing the final job. This
specification sheet will list the print parameters for the
particular file you be working on.
Figure 9-2. Spec sheet from a carton printer
A spec sheet typically looks like Figure 9-2.
Figure 9-2 is a typical
spec sheet from a printer that prints on various kinds packaging
material. Here's the information we should be concerned with:
The printer has indicated a curve; we will investigate this
They can print a variety of colors; this would mean that a
number of special colors could be used. It is very typical to use
special colors in packaging work because companies that sell goods
on store shelves want to attract your attention to their boxes and
The print process is flexo, or flexographic, which is a type of
press that can print on various packaging material, folding
cartons, plastics, and bags.
Substrates indicate the material to print on, such as a bread
bag. You probably won't care what material the image is going on,
but you will want to know what the specifications are for the image
so that it prints properly.
If we skip through the rest of the specifications in this
example, you will want to be aware of the following things:
What the press does to the image; this is very important.
The dot gain curve. We'll cover the dot gain curve in a
The minimum dot required for an image. If you have anything less
than the minimum dot anywhere in the image, the press will drop any
dots less than the minimum and they will not print. If you have a
soft gradation in a shadow or vignette, you may be disappointed to
find out that it breaks off where the minimum dot drops off.
You may or may not be concerned with the trap values. If you are
doing the trapping in Photoshop then yes, you would be concerned
with trapping. Trapping is typically done with specialized software
designed for trapping or packaging. Trapping is covered in Tutorial
The line screen required for the image. No point working on a
very large file at a high resolution if you're only going to be
using the image for the one job. You'll save processing time and
move around a little faster in Photoshop if your file is smaller as
Bleeds will be a concern for you. Bleed is the amount of extra
image you will need to have around the perimeter of the image that
extends out beyond the "live" area of an image, or what will be
seen when the final job is done. Extra image or bleed allows for
any shift when the printed job is cut or die-cut out of a printed
sheet. For example, when you see an ad in a magazine, it probably
had 1/8 inch or so of bleed around it, and the final magazine you
see was trimmed back or cut to the final magazine page size. If no
bleed is added, the page is trimmed to the correct size by a
cutter, and the cutter happens to trim the sheet or paper just
outside your image area, you'll have a line where the printed
material or paper pokes out along the edge where the cut was off or
where the image was offset when it was printed.
The rest of the specifications have more to do with the film
output or running the file directly to the printing plate and are
directed to the people who will be outputting the final files.