Producing prints with a soft hand is an ongoing challenge for garment screen printers. As merchandisers continue to press for softer and softer garments to bring to the retail market, screen shops must control squeegee pressures, ink-film thickness, and curing parameters. Many shops also employ various washing techniques to further enhance the feel of printed garments. In the following discussion, I’ll describe the most common types of garment washes and explain what steps you need to take in production to ensure that your prints survive the washing process.
Dozens of wash methods are used to alter the feel and appearance of a wide variety of fabrics, but only three types are primarily applied to T-shirts: enzyme, sand, and conventional water-washing, which is usually just called a garment wash program. These types of washes are more popular than ever because the current retail trend is for garments with a used or worn appearance.
Sand wash This method involves a large batch-washing cycle in which sand is introduced to abrade and soften the fabric. In most cases, the sand-washing process also has the same softening effect on the hand of the print. The abrasion of the sand-washing process wears away a portion of the print’s surface, resulting in a decoration with a softer feel than it had prior to washing. The print’s ink-film thickness, which I’ll discuss in detail later, ultimately determines the decoration’s softness and appearance after sand washing. The sand-washing process also removes a small amount of color from the fabric. The abrasion of the fabric causes fibrillation–fibers standing out or breaking loose from the printed ink film–which adds to the worn appearance of the finished garment.
Enzyme wash The enzyme-wash process is the chemical version of the sand wash. It uses special enzymes to soften the print and fabric and give the garment a “broken-in” look. The results an enzyme wash produces are similar to those of sand washing, but the enzyme method often is preferred because it is less expensive.
Garment wash With a conventional garment wash program, finished garments go through a standard wash cycle in a commercial washing machine. The agitation of the garments in water also leads to a worn appearance on the garments. However, sand and enzyme washes produce greater amounts of softness. Print abrasion in a standard garment wash is minimal to non-existent, but achieving fibrillation is possible if you print very thin ink films and use certain types of woven garment. For example, garments made with open-end yarns fibrillate less than those using ring-spun yarns.
Working toward the wash
If you want to produce a garment with soft hand and an abraded appearance, it only makes sense to aim for the softest hand possible when printing. But this also means you are limited in the type of decorations you can apply. For example, garments with special-effect decorations are typically not good candidates for wash programs because these types of decorations inherently have thicker ink films and a harsher hand.
The majority of the garments you will print for specialty washing programs will consist of flat, single-color decorations that are printed through screens with fine mesh counts. Typically, the designs themselves incorporate distressed effects that enhance the appearance of the print after it’s put through a wash process.
When engineering a print for a wash process, always remember that less is more. The thinner the ink film, the more apparent the results of washing will be. Printing thinner ink films also will make it easier to ensure that the decorations are cured properly, an important consideration for garments that will undergo a wash program.
Focus on flashing and curing
Whether the garment is headed for a specialty wash or the retail customer’s home laundry, you must properly cure every print in order to ensure the longevity of the decoration. The first and most basic mistake that a garment screen printer can make is under-curing the printed T-shirts.
Curing is of greatest importance with the sand- and enzyme-wash processes, which are harsher on the garment and print than the standard garment-wash method or home laundering. The last thing you want to see is a design break down too much in a harsh wash. An improperly cured print may survive the standard garment-wash process, but the decoration would most likely be abraded too much–or completely fail–in sand or enzyme washes.
Even though many graphics engineered for wash programs are single-color designs, there may be instances where you will need to print an underbase to ensure that a particular color retains a certain degree of vibrancy or opacity. In such cases, you should take extra precautions to ensure that you apply a proper cure to the underbase and overprinted color so that the inks properly adhere to each other, as well as to the garment.
I still encounter instances where press operators prefer to run their flash units hotter than necessary in the name of productivity. This can spell disaster if the surface of the underbase ink reaches 320°F, at which point adhesion with subsequent colors becomes impossible to guarantee.
When flashing an underbase, you only need to bring the surface temperature of the ink film to the point where the after-flash tack is minimized. The range typically is 190-250°F, depending on the ink you are printing. Once flashed, the wet overprint can properly bond, or fuse, with the underbase to ensure proper intercoat adhesion, and the underbase will form a strong bond with the fabric of the garment.
If you are fighting to beat the clock and flashing at too high a temperature, the underbase can quickly and easily reach 320°F and eliminate the intercoat adhesion between two ink films. The result can be a cured and durable underbase with an overprint that will abrade off completely during washing.
Keep in mind that even if both ink films are properly cured when passing through the dryer, they may not be properly fused together if the underbase was dried too thoroughly during the flashing process. Make sure to set your flash unit at a temperature that allows for maximum productivity and guarantees the integrity of the end product.
Test your techniques
Although you can’t employ these industrial garment-wash programs with residential-grade washing machines, you can use conventional washers to test the durability of conventional designs that don’t require the worn look. For your regular print runs, I recommend that you print a piece of scrap fabric or pull a printed shirt out of the production run for every 250 shirts you print. Wash test the sample to ensure that the print was cured properly and remains vibrant and firmly adhered to the fabric. In addition, you also should conduct regular tests on your dryer to ensure that you are reaching the proper cure temperatures. When you match designs to the wash process you use, control ink-film thickness, and properly cure your prints, you’ll end up with garments that last a long time, even though they look worn.
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