There
is often an ongoing dialog between artists
and production people about what is right
and wrong with a printed image. In many cases,
the production department feels that "if only
the artist had done it different - it would
have printed better." The artist's comeback
is - "I didn't know that mattered." Since
many artists aren't trained in screen printing,
you can't really blame them. In fact, when
I work with large companies I encourage them
to get artist's on the production floor and
let them see how that end of the business
runs.
With
that in mind, this article is written to help
artists better understand the screen printing
process and to be more responsible for the
outcome of the final print.
-
Take
charge of the specifications.
This may be contrary to many shop's thinking,
but I personally feel that if you "built
it" then you know what you had in mind.
You should specify the print sequence,
the mesh counts, the number of flashes,
etc. (Figure 1) If you feel uncomfortable
doing that, then the rest of this information
should help. If nothing else, take time
to work a few hours in the Screen Making,
Ink and Production departments.
-
Get
a production sample of every job. Learn
from each job.
It always amazes me when artists tell
me that they don't see the final shirt.
After I pick my self up off the floor
from shock, I wonder "what the heck is
wrong with that company? You can't afford
to give the guys who built the image a
production sample to learn from?"
-
Determine
the correct color sequence.
On a light colored shirt, we generally
print light to dark, or smallest amount
of ink to the most amount of ink. The
reason for this is that inks pickup on
the back of the screens and you don't
want dark colors contaminating lighter
colors (figure 2).
On
dark shirts we generally print a base
of white ink that is either a solid or
halftone dots. This base must be flash
cured and then colors are printed on top.
A typical color sequence is light to dark
BUT put any large ink area or dominant
and important color last in the sequence
(figure 3).
For a real Process Color (CMYK) job, use
the order of YMCK and put any spot colors
after their like process color - red after
magenta, etc. (Figure 4)
-
Recommend
the mesh selection.
This one will vary depending on the type
of work you shop does. For general simple
designs use a 45 (cm) mesh. For more complex,
move up to 77. For more detailed jobs
with lots of halftones use a 90 to a 120
mesh. For dark shirts you should use 77
to 90 for the underbase and 120 or higher
for the tops colors.
-
No,
this isn't paper printing.
Forget most of what you learned in art
school about paper printing. We take a
great image and then just mess it up by
converting it to large halftones (55 lpi
to 65 lpi) and then put these dots on
a screen mesh, and THEN we print these
halftone dots on a knit shirt. Nothing
will look the same.
Even
thought we do print some images with process
color, most of our work is done with spot
colors. On dark shirts we DON'T print
CMYK process colors because they will
become very dull when printed on an underbase.
Instead we print dark shirts with standard
spot color inks on a base of halftoned
white ink. This is called "Fake" or "Simulate"
process color.
-
What
you see is not what you always get. (WYSINWYAG)
Yes, the image on the monitor looks great
but that is NOT what you will get when
it is screened. We already talked about
how we mess up the image. Everything get's
FATTER when we screen print it. This is
called "dot gain." If you have a 20% density
area in an image, chances are when you
convert this to a 20% halftone dot and
print it, the dot will grow up to 40%.
You will now have almost a 30% dot on
the shirt. This gets worse in the shadow
areas. Your 70% dots might print as a
solid. You must always think lighter when
creating color separations to allow for
all the dot gain (figure 5).
-
Cut
the production guys some slack.
It is easy to sit in your art department
and make minor tweaks after they show
you the production sample. Give the production
guys a break. A minor change of two or
three colors means re-burning two or three
screens, pulling the old screen off the
press, setting up the new screens, getting
them in registration, making a test print,
etc., etc., etc. This is NOT easy.
Matching colors is the same. It is very
hard to match that little color chip printed
on glossy paper with the color on a knit
shirt (figure 6). Try to be flexible here.
-
Try
to talk the same language.
I deal with artists every day and find
that there is often two different languages.
A production person might complain that
the Red isn't bright enough on the black
shirt. You might wonder why the red isn't
brighter, when in fact the red has nothing
to do with it. Red generally needs to
be underbased on a black shirt and it
could be that your underbase isn't bright
enough, OR, that the production people
need to make the underbase brighter by
slowing down the squeegee stroke, using
a lower mesh count, changing the angle
of the squeegee, or using a more opaque
white. This will in turn make the red
brighter!
-
Know
your shop's limitations.
There is no reason to expect your screen
making department to hold a 2% dot on
a screen. It is just not done. (OK, I
know some of you can do it.) You need
to do a test film with various densities
from 5% and higher that your screen department
can burn. Have them make a print and see
what happens. Also, if your shop doesn't
use properly tensioned screens, you might
get 50% to 60% dot gain or more. Allow
for this when using halftone dots.
If
your shop can't hold almost perfect registration,
think about overlapping the black and
colors from 2 to 4 points on spot color
jobs. This is called a trap and has been
covered in previous articles.
These
are just some of the things you should think
about when doing color separations for screen
printing.
|
