Screen Printing has been around since the days of the Romans. Of course, it is much more
sophisticated now. I will walk you through the steps below to show you how your graphic is printed on your shirt.
Art Work:
The first thing we do is come up with the graphics you want to print. Before we can
design a graphic for you, we need to know a few things.
What color is your Shirt?
How many Locations? (Front, Back etc.)
How many colors do you want to use for the printing of each location?
Most Screen Printing is
accomplished using "Line Art". This is a type of art that has specific colors for
each color used in the printing. Think of "Line Art" as a coloring book where you color inside
the lines. The "Shirt Shack Omaha" logo above would be 2-Colors (Red and Black) on a white shirt, but
if I wanted to print that logo on a Grey shirt, and I wanted the white in the logo
to be white, I would need 3-Colors (Red, Black and White). We can achieve different
shades of the same color using half tone screens. We would need to look at your
Graphic to give you the details.
The more colors you have in your graphic, the more expensive the printing will be.
This is something to keep in mind when pricing your shirts. Graphics with photgraphs must be
printed using a special process called "4-Color Process". This type of printing uses 4
different colors to achieve thousands of other colors by overlaying 4 primary colors on top
of each other. This type of printing can only be done on 100% Cotton white T-shirts.
Because of the expense of setting up this type of printing($200.00), we do not recomend this for less than
200 pieces.
Film Positives:
After the Graphic is approved by you, the next step is to create "Film Positives." This is achieved
by "Color Seperating" the graphic into a positive image for each color. We use a product called
"Vellum" that we run through the Laser Printer. There is one page of vellum for each color used
on the print. Each piece of vellum has a black image printed on it that is an exact copy of the color we want seperated.
All the colors are "Butt Cut" which means they "Butt" up against each other when printed. There
is no overlap (Trap) used. 4-Color Process Seperations use whats called a "Line Screen" for the seperations.
This is a series of very small dots that vary in size and density. There are 4 different positives used for these seperations.
We use a clear film for these seperations to achieve better screen results.
Making Screens:
After we have the positives ran out, the next step is exposing the screens. The screens
are coated with a light sensitive emulsion and dried in a Screen Room that has a special type
of light to prevent them from exposing. Each positive is placed on the bottom side of a
screen (The "Print Side"), aligned, and taped into postion. The screen is then placed in
the Exposure Unit. This is a piece of equipment that uses a 3000 watt bulb to expose the
image on the screen. The light passes through the vellum and exposes (hardens) the emulsion
that has been coated on the screen. Where the Black image is printed on the vellum, the
light is blocked and the emulsion stays soft. After the image is transfered to the screen
(The screen is "Exposed"), the screen is taken out of the Exposure Unit and the vellum removed.
The screen is then taken to a washout booth and sprayed with water. The soft emulsion washes
out while the hardened emulsion stays on the screen. Where the emulsion washes out
is where the Ink is allowed to pass through the screen. The screen is then allowed to dry.
We then check for pinholes(Imperfections) and block out anything we don't want to print.
After that, we tape up the sides and it is ready for printing.
Setting Up The Press:
Our screens are ready, now we can set up the Printing Press to run our job. We can only set up and
print one location (Front, Back, etc.) at a time. If your job has more than one location, then we must tear down and setup
each location to print the entire job. The printer will start by gathering all the screens for that location
and loading one head of the Printing Press for each screen. The printer then lines up the first
screen to the Pallet (The shirt board that the shirts are printed on).
If your job has more than one color, then each color must be lined up to all the other colors before we can start printing.
The printer will put ink in each screen, attach a "Squegee"(the device that pushes the ink through the screen and
onto the shirt) and a "Flood Bar"(this floods the image with ink, for the squegee to print) to each head. The printer will "Strike Off"
one test print and check
the print to make sure it is lined up correctly and there are no imperfections in the screen. After
the printer is satisfied the print looks good, they will take it to the Art Department for final approval.
Printing:
Now, we are ready to print our job. The printer stacks all the shirts flat with the location
they want to print facing up. They load the shirts one at a time onto the Printing Press as
the Press revolves around. Each head of the Printing Press prints one color from the graphic
on each shirt, and when
it revolves around to the end, the printer checks the print, removes the shirt from the press, and loads
another shirt.
Curing:
After the shirt is removed from the Printing Press, it is placed on a conveyer belt that
carries it through the heat chamber (The Dryer) where the ink is cured. We use Plastisol Ink
that must reach 315 degrees for 15 seconds to cure. After the shirts exit the dryer, they are
checked for the printing quality once again, and stacked up by size. If there is another location
to be printed on the shirts, they are flipped over to be ready to be printed again.
Packaging:
When the shirts are finished, we stack them by size in stacks of 12 pieces or less. We use whats called
a "Printers Fold" and fold them up in 12 piece bundles. The shirts are placed in a box and the box is marked
with the size and quantity in each box. The job is now finished.
If you have any more questions, please feel free to call or email us.
To contact Shirt Shack Omaha by e-mail: sales@shirtshackomaha.com Return Home
