A Guide to All Things Screen Printing

Introduction:

Screen printing is a technique that applies ink to a garment through a woven mesh that has a stencil of a logo or design on it, whereas embroidery applies a design with thread. Screen printing is typically lower in cost than embroidery. Screen printed shirts can commonly be found in gift shops, with a design printed on the front or back or both sides of the garment.

Screen printed designs can be applied to a shirt or other garment in either a full color image such as replicating a photo or by spot colors where the design is made up of just a few discrete colors. The full color process is quite expensive and typically reserved for special applications. Common applications for company employees, special events, charities, family reunions and so on are done with spot colors.

Steps in the process:

1. Provide a copy of the logo or design(s) and specify the location(s) to be printed.
2. Determine the number of colors of ink in the design(s) and pick the colors of ink
3. Choose the garments(apparel), color of garments and the total quantity.
4. Create the artwork and proof
5. Create the screens – also known as the “Set-up” process
6. Obtain the apparel
7. Select the ink color(s) or if needed mix them
8. Install the screens onto the printing machine
9. Do the printing
10. Dry the garment
11. Fold, pack, and ship the order

Details:

1. Supply your logo or design. You may want to have one design applied to the front or the back of a T-shirt. Or you may want different designs to be applied to different locations on the shirt. If you simply want text such as “Hansen Family Reunion July 2013” for example, we can generate that for you. For more complex designs you will need to supply the completed artwork in a jpg or pdf format and eventually in a vector format such as an .eps or Illustrator output or .pdf vector file. If you do not have a logo and cannot create one yourself, you may want to contact a graphic artist to design one for you. A graphic artist will be familiar with all the file formats needed.
2. Determine the colors of ink to be used on your design. The more colors of ink you use the higher the printing cost. Also if you print light colored ink such as white or light pink on a dark garment, that is more costly than printing a dark color like black on a light colored shirt. Typically each design will be treated like a nearly separate order since most of the steps will need to be repeated. As an example if you want a print on the front and the back, we will first print all of the fronts and then print all of the backs.
3. Choose the color, style, sizes and quantities of the apparel. If you want to have a design printed on different colored shirts, say 36 black shirts and 36 yellow shirts and you wish to use different colors of ink for these two applications, it will be necessary to change the ink color when switching from black shirts to yellow shirts.
4. The “set-up” process involves doing several things all involving turning your logo/design into to screens.
   1. We first have to insure that the digital files we have are vector files. These files allow the design to be scaled to the appropriate size without losing resolution. This also also allows for multiple colors to be printed.
   2. We will create a “proof” which shows your design superimposed onto the garment. This is emailed to you for approval.
   3. We will then “separate” your design into its various “ink” colors. If your design has 3 ink colors we will create 3 separate stencils, one for each color. We will then print these separately on a transparent film in the exact size needed for the final printing.
   4. In the next step we create the screens. This involves applying a light sensitive photo emulsion to a screen. The screen is a wood or metal frame with a woven material such as polyester stretched tight over the top of the frame. Prior to the advent of polyester, silk was a common material for the screens. This is where you get the term silk screening from. The clear film with the stencil of the design is perfectly aligned onto the screen and temporarily attached to the screen. All of the work associated with preparing the screens must be done in a dark room, much the same as if you were developing film.
   5. The screen with the light sensitive coating attached stencil is placed on a light table. A special light source is used to expose all of the light sensitive emulsion except for those portions covered by the stencil.
   6. Next the screen is spray washed to remove all the unexposed emulsion. The portion of the screen covered by the stencil will be unexposed and will wash out, leaving the image of the stencil open and now able to allow ink to pass through. Have a look at this video to see the process:
   7. If multiple colors are called for, then a separate screen is similarly created for each color.
   8. The next step is to mix up or obtain the correct ink required for each screen. This can be either a standard color like white or black or one of a number of common pre-mixed ink colors. The color can also be a special color shade picked from a Pantone chart, which is a large pallet of industry standard colors. These are much like the color cards you find at your local home store when selecting wall paint. The Pantone colors are identified with a PMS#, which specifies the formula we use to mix up the proper ink color.
   9. The next step is to set-up the automatic printing machine. This involves installing each screen into a clamp and then adjusting the X-Y and rotational registration of the screen very precisely using registration marks that were printed onto the film we generated in step # 4c. Each separate color of ink calls for its specific screen to be installed into a separate station and registered in exactly the same fashion. If your print called for 3 different colors of ink, for example a tree trunk with brown ink, the leaves with green ink and text below calling for black ink there are 3 screens and stations. Each has to be aligned precisely so that when the green leaves are printed onto the brown branches, they appear to be attached properly.
   10. Start the presses! The printing can now begin. Most modern machines are automatic. After the screens are in position, the operator will apply a generous portion of ink onto each screen, being careful to apply the correct color onto each screen. The operator will then install one garment at a time, typically a T-shirt, onto a “platen” which is a flat plate that holds the shirt secure while the ink is applied. Typically a special “sticky” spray is first sprayed onto the platen to help hold the garment in place. The placement of the garment onto the platen is not as critical as the screen alignment process is but is important to insure that the placement of the print is in the correct location; not too high or low, not rotated on the shirt, and so on. When the press starts up it will rotate the platen to the first station and stop. The machine will move the screen down and contact the shirt. A large squeegee, which is part of the machine, then moves across the screen, dragging ink with it and thus forcing the ink down through the open pores of the screen and onto the shirt. When this is finished, the machine lifts the screen up and off of the shirt and then the platen is rotated to the second station. The process is repeated at the second station with the second screen being rotated down and into contact with the shirt and the second color of ink is squeegeed onto the shirt. As the first station is applying the first color of ink, the operator will install a second shirt onto a second platen so that there will be a continuous flow of shirts and each station is active at all times. The video below shows a multi-head automatic press cranking out shirts. These machines can produce hundreds of printed shirts per hour, once they are set-up.
   11. The next to last step is drying. Most common inks are dried with heat to speed up the process and to “fix” or cure the ink so that it will remain on the shirt through multiple washings. Most companies will employ a conveyor belt dryer that slowly runs the shirts under a heat source and out the other side dry. This is similar to the devices used in many fast food restaurants to heat sandwiches.
   12. The last step is to count, fold, and pack the shirts for shipment.