The most common decoration method for custom apparel is traditional direct screen printing. Direct screen printing is ideal for larger quantity orders and typically artwork with fewer print colors. The print price comes down to how many colors are in the artwork, how many total pieces are being printed, and the type of screen printing ink being used. Screen printing is very unique in that it can be used for “spot printing” or “process printing”. Most apparel prints are spot printing with each color in the design requiring a separate screen and the specific ink color being mixed to print the artwork. Where as process printing also referred to as CMYK printing involves printing Cyan, Magenta, Yellow, and Black to create full color artwork just like an inkjet or laser printer. Screen printing is truly an art that requires more skilled labor than any other decoration process.
Plastisol Ink
The majority of screen printed apparel is done by so by using some type of plastisol ink. Most plastisol ink manufacturers offer a universal, soft-hand, max-opaque, low-temperature, puff, metallic, glitter, reflective, glow-in-the-dark, blacklight, and color changing, among others. Each type of plastisol ink has its time and place with some requiring more printing experience than others to execute perfectly. A screen printer will judge the quality of a manufacturer's ink product based on how easy it is to print with, its opacity, its hand (feel), and durability. Most customers are primarily worried about the print being opaque and the right print color. Secondly, they worry about what the ink feels like. So, opacity is typically a screen printers main goal when printing an order.
Waterbased & Discharge Ink
Plastisol inks will always be the primary type of screen print ink used in the industry, but retail brands often demand high quality and that is where waterbased and discharge screen printing come into play. Waterbased and discharge ink have started to become more popular for retail brands because the ink has essentially zero feel. The problem with discharge and water based inks is that they have a more limited product line / product colors that can be printed. Another drawback of waterbased and discharge ink is that they have a very short life span compared to plastisol inks which never go bad or dry until they reach over 200 degrees.
How the Screen Printing Process Works
The screen printing process begins with the artwork. The artwork should be in vector format to be screen printed. While bitmap artwork can be used to screen-print, vector is a much easier format for screen printers to handle. Vector artwork scales better than bitmap and prints better because it groups and holds colors. Since bitmap images are composed of thousands of tiny pixeles the color is less consistent. Once you have suitable vector artwork, the colors in the artwork must be separated. This is because screen printing is “spot color,” which means that each color must be printed separately rather than blended. Once the artwork is color separated, each color must be printed onto its own transparent film positive.
Each film positive must then be taped to a screen that is coated with a photosensitive emulsion. The screens are then exposed to UV light in a darkroom equipped with safelights for approximately 30 seconds. This binds the emulsion to the screens in the areas around the artwork. Next, the screen printer will remove the film positives from the screens. The screens are then power washed to remove the emulsion that was beneath the artwork on the film positives. When the screens have dried, they are ready to print.
The screens are loaded onto a screen printing machine (typically a carousel) where they will be used one-by-one to print each color on the desired garment. The screen printer will then place the correct ink color on each screen and lower the screen onto the garment. Ink is printed by pulling a squeegee along the length of the screen, forcing the ink through the mesh and onto the garment. Depending on several factors, including the type of ink, the garment might need to be “flash dried” between each color so that the next layer of color is not laid over top of wet ink that could cling to the screen and ruin subsequent prints. Screen printing is similar to painting a wall in that, unless you are using very opaque ink, a white underbase may be necessary to make the colors pop.
Once all the colors have been laid, the garment is removed from the screen printing machine and placed onto a conveyor dryer. The conveyor dryer will carry the garment through an oven that will cure the ink to it. Curing solidifies the ink and is directly responsible for the print’s durability. If the ink is not cured properly, then the print can crack or peel after being washed.
The Pros & Cons of Direct Screen Printing
Screen printing is the least expensive method of apparel decoration, while also providing one of the most vibrant and opaque prints of any printing process. Most of the print costs are derived from the setup process, rather than the printing itself. It is also the most durable printing method, however screen printing is not without its drawbacks. The aforementioned artwork requirements can be an impediment to completing a print job. It can also be very expensive to create full color prints or even prints with over four colors. The biggest issue with screen printing is that it requires a minimum of 12 pieces for an order. It is simply just not economical to go to all the effort of creating screens and printing in order to make a single garment.
Screen printing is a game of variables. It is an intricate process that requires effort and attention to detail to master. When you consider the artwork, the screens, the emulsion, the types of ink, screen alignment, the curing process, and operation of all the involved equipment, there is ample opportunity for mistakes to happen. It will take a lot of trial and error for beginning screen printers to familiarize themselves with the process and perfect their technique. That effort will be worth it as the printing volume capabilities of screen printing are unmatched among other decoration methods.
As previously stated, screen printing is the most common form of apparel decoration. Schools, businesses, and organizations are common customers for screen printers since they typically will order large numbers of the same prints. If you are looking for a large run of prints with 3 colors or fewer, then screen printing is your best option. However, before you go off to purchase screen printing equipment, you might want to considering outsourcing screen print transfers and applying them using a heat press.
