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Garment Printing



The cost of raw materials for garments has changed over the past several years along with the garment market itself. Even though cotton remains the most widely used material in apparel manufacture, environmental disasters around the world have devastated large portions of the global cotton crop, thereby causing the prices for cotton to skyrocket.

The cost of raw materials for garments has changed over the past several years along with the garment market itself. Even though cotton remains the most widely used material in apparel manufacture, environmental disasters around the world have devastated large portions of the global cotton crop, thereby causing the prices for cotton to skyrocket.

As you might imagine, these higher costs have prompted apparel manufacturers to offer garment lines that make use of more synthetic blended fabrics to offset the more expensive cotton. In addition, they’re presenting garment styles in thinner and thinner weights. The combination of the increase in synthetics and the decrease in garment weights challenges the garment screen printer to determine the best way to embellish these fabrics without hindering the performance of the ink film or the fabric.

Where most lightweight T-shirts weigh in at 5.5 oz., we now have fabrics that weigh in the low 4-oz. range, which makes the printing process similar to printing on gauze. It is here that the printer is faced with the challenge of creating a graphic that will pop while maintaining the softest hand possible.

As garment screen printers, we must develop the mindset that we, in essence, need to follow the same basic laws that apply to printing on heavyweight fabrics—except that we must decrease the overall ink-film thickness while maintaining the aesthetic qualities of the graphic. Let’s review the aspects of the process that maximize graphic effects and maintain the softer feel of the fabric.

Artwork engineering
Printing on lightweight fabrics of this nature successfully requires that you avoid solid ink films as much as possible. Art designed with broken image areas or distressed graphics that break up the image are ideal for lightweight garments. The basic rule for printing on these styles of garments is to stay away from the classic, heavy-handed, athletic graphics and most special-effect inks. Lighter fabrics also lend themselves to muted or rustic graphics that possess a degree of transparency. Water-based inks are preferable lightly colored fabrics, although plastisols are a must in many cases as many are blended fabrics.

Lightweight fabrics typically are constructed with thinner yarn and a looser knit than their heavyweight counterparts. This poses a true challenge for any job that involves halftone reproduction. For facilities that print halftone on a regular basis, I recommend testing a garment with whatever typical line count you would print with as a standard. If the results are unacceptable, you may consider moving to a coarser halftone line count to compensate for the coarser knit of the garment fabric.

Rethinking your approaches to screens is an important part of screen printing lightweight fabrics. Some of these fabrics are so loosely knit that you may wish to avoid even attempting to bridge the knit of the fabric by staying out of the material’s voids, much like you would when screen printing nylon micromesh.
You can print lightly colored fabrics with a 230-thread/in. mesh higher using a 70/90/70-durometer or standard 80-durometer squeegee. For direct applications darker fabrics, where underbases are required, you should keep the mesh count in the 155- to 180-thread/in. range. Using the previously mention squeegee parameters would work in this scenario as well. The overprint mesh counts would again fall in the 230- to 305-thread/in. range.

As with most applications, highly tensioned screens are beneficial and allow you to deposit thinner ink films onto the surface of the fabric, as opposed to driving it through and onto the platen. Maintaining the soft hand of a garment print is the perfect time to put the less is more philosophy to work.

Because your objective in printing lightweight fabrics is to maintain the soft hand of that fabric, you are somewhat limited in your choices of ink formulations. The lighter colored, 100% cottons lend themselves to water-based inks. You have the option of discharge printing for the darker cottons, but you should always test this process on the garment before going into full-scale production to ensure you will achieve satisfactory results with that fabric.

Many of the lighter fabrics on the market are either cotton/poly blends or tri-blends, which means you may be restricted to using plastisol inks. These fabrics may range from simple fiber combinations to a three-way mix of cotton, polyester, rayon, or spandex. These fabrics—the tri-blends, in particular—require garment screen printers to rethink their mesh selections with the goal of minimizing ink-film thickness as much as possible and, ultimately, maintaining the original soft hand of the fabric.

Most garment printers select bleed-resistant inks for jobs that involve blended fabrics. I suggest modifying these inks by using a reducer or a soft-hand additive to increase their flow characteristics. Be careful when using these modifiers. There is a fine line between improved ink flow and a harmful reduction in an ink’s opacity.

Three additional alternatives are available when it comes to embellishing lightweight fabrics: heat transfers that produce a relatively soft hand, direct-to-garment inkjet printing, and sublimation transfers. Although all are multistep processes, they do offer the ability to reproduce a soft-handed image on lightweight materials. Be sure to pre-test the garment when using any transfer process that involves the application of heat. Blended fabrics are, at times, sensitive to heat, which can lead to unwanted platen marks on the garments.

Most garment inkjet printers are designed for cottons. Not every system can handle cotton/poly blends or more complicated fabric compositions. Consult with manufacturers before you think about making a purchase. Many printers use sublimation transfers when decorating lightweight fabrics. Although the sublimation transfer is not true dye-sublimation printing, it can often resolve issues associated with printing inks onto light materials.

Curing parameters
Curing isn’t often something for most garment screen printers to worry about when working with 100% cotton apparel, although you may want to test to ensure that the garments you’re printing do not carry excessive sizing that will at times discolor under normal 320°F curing conditions.
Blended fabrics should be measured before and after the curing process to ensure that there is no fabric shrinkage taking place while passing through the dryer. Should you find excessive shrinkage as a result of heat exposure, you may wish to use a low-temperature plastisol in an effort to lower the overall heat exposure to the fabric.

Rick Davis has been involved in textile screen printing since 1975 and has served as president of Synergy Screen Printing in Orlando, FL, since 2004. He is a contributor to industry trade publications and a member of the Academy of Screen Printing Technology.


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