So, you’ve selected your t-shirt fabric, finalized your design, and placed your order. What’s the next step? The initial phase involves creating films for each color in your design. A skilled graphic artist will analyze your artwork to determine the most effective color printing method.
The two primary color printing techniques are spot color and four-color process. Spot colors are individual, pre-mixed hues printed independently. There’s a vast selection of pre-mixed colors, and countless others can be created to precise specifications, such as those within the Pantone Matching System.
Four-color process, also known as CMYK, blends four colors – Cyan, Magenta, Yellow, and Black – directly on the fabric to produce a wide spectrum of colors. This method is ideal for replicating photographic images and graphics that feature intricate shading and textures. Simulated process printing, a hybrid approach, combines elements of both spot color and four-color process techniques.
The graphic artist generates transparent acetate films for each color, printing them in black along with registration marks and essential information. These films, accompanied by detailed printing instructions, are then sent to be transferred onto screens.
Each color in your t-shirt design is exposed onto a fine mesh screen coated with a photosensitive emulsion using a high-intensity lightbox. These screens were historically made of silk, hence the name ‘silkscreen.’ Upon exposure, the emulsion hardens and becomes water-resistant. The black areas on the acetate film block light from reaching the emulsion beneath. The unexposed sections dissolve in water. The screen is then placed in a high-pressure washing unit to remove the unexposed emulsion, leaving behind a detailed stencil for that specific color of ink.
While the Art Department prepares your films, your t-shirts are ordered from wholesale suppliers. Locating specific sizes or colors can sometimes be challenging. Once the textiles arrive, they are carefully counted, checked against the order for accuracy, and then transported to the screen printers.
A multi-head press accommodates multiple screens, ranging from four to sixteen. The screens are arranged radially and rotate over palettes onto which the t-shirts are placed. Presses can be either automatic, where rotation is pneumatically controlled, or manual, where the printer physically rotates the press. Each screen is secured onto a bracket, or head, and locked in position. The printer meticulously aligns the printed images from each screen to ensure accurate registration for the final, composite image. The appropriate ink color is applied to each screen and forced through the screen’s openings using a squeegee, pulled from the bottom to the top. Several factors influence the final silkscreen print, including the squeegee’s hardness, the angle and pressure of the pull, and the type of ink used.
Following printing, the t-shirts are passed through a high-temperature dryer to cure the ink, ensuring it bonds securely to the fabric fibers. A final test print is approved by the graphic artist, and then the full run of t-shirts is printed.