Screen Printing has been around since the days of the Romans.  Of course, it is much more sophisticated now.
Below are the steps 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, left chest, 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, it 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 photographs 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 recommend 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 separating" 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 separated.  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 Separations use what's called a "Line Screen" for the separations.  This is a series of very small dots that vary in size and density.  There are 4 different positives used for these separations.  We use a clear film for these separations 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 position.  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 "squeegee"(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 squeegee 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 conveyor 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.