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Understanding the Garment: Selection, Testing, and Prep

What you need to know to get the best possible print.

Quality screen printing of apparel begins with the garment itself. The garment impacts every other variable in the process, and understanding how it does so is central to achieving the best possible result. Stitch count, finish, weight, thickness, and fabric properties such as the potential for dye migration and heat sensitivity, as well as the material’s construction and color, all affect the print, and need to be considered in the production process. They may influence the mesh you choose for the job, the ink you select, the print/flash sequence, and much more; these factors, in turn, determine the quality level at which a specific piece of artwork can be reproduced on a particular garment.

Selecting the Garment
When evaluating a garment for screen printing, a good place to start is stitch count, says consultant Charlie Taublieb. “The more stitches, the smoother the fabric, allowing for a sharper print,” he explains. “Heavyweight fabrics feel good, but have so much fiber that fibrillation or fabric show-through could be an issue. The 50/50 garments usually are thinner and, for this reason, often produce a sharper looking print.”

Today’s popular performance fabrics can also enhance print quality, though they present unique challenges. “Performance fabrics are generally polyesters of some kind and usually pretty smooth, allowing for a sharp print,” he notes. “The biggest problem with them is the potential for dye migration. This may require using inks that are quite thick or an underlay as a blocker, which may result in a print that doesn’t have the hand that’s desired. However, using a roller squeegee [after flashing] can help to smooth out the surface and allows for a very flat and vibrant print.”

Tri-blends, Taublieb says, are another story in production. “Because of their higher stitch count, many take ink smoothly, but not all of them. Some are more ‘fibery’ than others, and it is often difficult to achieve a smooth look. However, flashing is where the biggest problems occur with these fabrics, and it needs to be considered in your printing strategy. Quartz flash units tend to run very hot where the bulbs are and cool between them, making it difficult trying to flash without shrinking the fabric where the bulbs are. I prefer infrared flash units when working with tri-blends.”

The garment’s properties must then be considered with respect to the type of image to be printed. “If the design has very fine detail, for example, a smoother printing surface and/or higher stitch count may be of particular importance because it holds detail better,” says Taublieb.

Oftentimes, knowing how well a garment will work with a given piece of art is a matter of experience with the manufacturer and product line, say veteran printers. “Each brand and shirt style has its own characteristics,” states award-winning printer Andy Anderson, Anderson Studio. “Over time, you gain an understanding of what you can expect from a certain garment line in terms of printability and also consistency.”

Printers don’t always get to choose the garment for the job, however. In situations like contract printing, it may be stipulated or supplied by the customer, whose choice is more likely to be dictated by look, cost, or loyalty to a brand or style than how well the garment lends itself to screen printing. Anderson’s business currently consists largely of this type of contract work: “The customer wants something he’s seen online or in another context and specifies it. When you get a sample, you have to evaluate it with respect to the art to be printed and make some choices.”

Like Taublieb, Anderson looks first to the fabric type when evaluating a garment, as well as the style, weight, and stitch count. “I consider the brand and style as well. It’s important to know if you’re dealing with a manufacturer that has decent quality control and whose garments are going to be consistent with minimal dye migration, particularly with respect to blends and performance wear.”

Anderson keeps detailed records of previous orders including the garment specifications, allowing him to reference how similar garments were printed successfully in the past. “This type of documentation comes in really handy in determining what you’re getting into when printing on a specific garment and challenges you’re likely to encounter. It also streamlines production by providing guidelines for printing, flashing, dryer speeds and temperatures, etc.” Such records can remind you that you got better results by preshrinking a nylon jacket, for example, or that you ran a heavyweight garment through the dryer prior to printing to remove excess moisture that inhibited curing.

If you’re not familiar with a brand of garment, Anderson suggests investing in samples to compare with other brands in terms of fabric, cut, and size. Also consider contacting a recognized expert via social media or going to one of the online forums and asking other printers to share their experiences (taking the source of the advice under consideration). You have several options if you don’t think the customer’s choice of shirt will work for the job. One of the best, experts agree, is to show the customer alternative garments with a similar look and fit that are better suited to the job. “It’s important to explain to the client why a particular fabric might not be the best choice for his needs,” says Taublieb. “Having samples of a similar design printed on a variety of garments can be an effective way of showing the effect of the garment on the print.”

Anderson also suggests having printed samples on hand to illustrate the point. “If there is a difference between the material of the customer’s garment choice and that of a better printing one, it can help to let him see and feel it for himself while you explain its effect on how his job would print.”

“But in the end, it’s the customer’s choice,” Taublieb cautions. “And while you can attempt to help him make an educated decision, you don’t want to get into all the issues the garment he has selected is going to raise for you as a printer. As screen printers, it’s about doing our best no matter what the fabric is.”

If you’re locked into printing on a garment that’s less than optimal, then you have to explore the printing variables you can change, such as mesh counts, inks, squeegee hardness and pressure, print speed, and more, to compensate.

First, consider how the artwork might affect your printing strategy. For Anderson, key considerations relating to the image include ink coverage and the number of colors to be printed. “If I have to cover a lot of the shirt and it’s a full-color print, I have to use a different approach on a 50/50 or other polyester blend shirt than on 100-percent cotton,” he notes. “For instance, I know I’m going to have to use a low-bleed ink to prevent the shirt dye from migrating through the white base and bleeding into the overprinted colors and/or dulling the image, which will affect the feel of the print. But I have to make sure the customer understands that there will be a compromise.”

The art-garment pairing can also indicate the need for different separations and mesh counts. “Whereas on 100-percent cotton, you may be used to running a 55-line halftone, on a 50/50 garment – if the design isn’t too detailed – you may want to consider going to a 45-line,” Anderson suggests. “This would allow you to use a lower mesh count to lay down a little more ink to cover better and get a brighter print.” It’s also a strategy to keep in mind for underbases on dark shirts, he notes.

The color of the garment should be considered, not just for the job at hand, but also for potential future runs. If there’s a possibility the job you’re running on a white shirt now may later be printed on a dark one, you can factor that into the number of lines per inch in your halftones and choice of meshes to put you ahead of the game. “It’s not a bad idea to ask your customer up front whether he thinks the image will ever be printed on another color or different type of garment.”

These variables – the design, garment color, and fabric type – often determine the best techniques for printing a job. “An example is performance wear or dry-wicking garments,” says Anderson. “A lot of times, a customer wants a nice, light print on a color like royal blue or red, which are typically the combinations most susceptible to dye migration on any fabric, and more so on these. The design may have tiny fonts that are reversed out in a solid area of white ink and two- or three-point lines, and you can’t put enough ink down to block the migration; so you have to find a compromise. In many cases, what works for us is putting the design on a higher-count mesh, quickly flashing it, and then putting down a second layer and hitting it again.”

Anderson cautions that this technique doesn’t work on all garments. “A lot of printers will do two hits to get a nice white on a shirt, flash it on the press to semi-cure it, and then print another layer of white over it to add brightness. But if you use this technique on a heat-sensitive fabric with the same temperature and dwell time as you would on a 100-percent cotton shirt, you’ll end up shrinking or burning it. So you have to make adjustments. You have to turn down the heat and really monitor the amount of time the shirt is under the flash so you don’t overheat it.”

Test for Success
The best guarantee of getting a quality print on a specific garment is experience. Although testing isn’t always practical, it can make a critical difference when you’re dealing with a garment for the first time. “This is especially important with all of the new fabrics that are being introduced,” says Anderson. “If you’re not used to printing on one of these blends, the best advice I can give is to test it. Do a sample print and document every step. Then let the garment sit for a while to see what it does – whether the colors leach or bleed. Keep alert for differences in how the print responds to variables like dryer temperature and belt speed, and note things like how forgiving the fabric is and how well the ink bonds to it.”

Anticipate the need for testing up front and you can begin educating the client from the outset. “If we’re dealing with a garment that’s an unknown quantity, or we’re skeptical about its suitability for a job, we’ve learned to tell the customer to please order a few extra so we can do some testing to make sure that the inks that we use and the type of print that we’re doing on it will be acceptable.”

As you encounter difficulties in testing, don’t hesitate to look for answers from your suppliers. “Ink manufacturers are a valuable resource here,” Anderson notes. “The movement to new fabrics has sparked quite a bit of research on the ink front, and sales reps can contact their tech departments to get assistance with respect to which inks and techniques to try.” Taublieb adds that the manufacturer may have a better product for the challenge you’re facing, such as a newer formulation with improved resistance to dye migration.

But don’t fall into the trap of blaming the ink for any problems that occur. Monitor your equipment and how it’s set up as well, Taublieb suggests. “For example, it’s a good idea to use heat strips or a temperature probe and compare the reading to the one on your dryer for a ‘reality check.’ Then run a sample print at various temperatures and belt speeds and check for cure, migration, and overall print quality. You can’t over-check, and the time it takes to test will pay off in reducing rejects due to dye migration, poor adhesion, etc. A little precaution goes a long way. There are better controls on equipment today that enable you to get an accurate read on what your machines are doing and allow for more precise settings.”

He also suggests taking advantage of slower business periods to do some R&D that will build your expertise. Understanding the challenges will point you toward newer technologies that may overcome them, information that’s readily available and important to running a successful screen-printing business.

“The process has become a lot more refined, and there are answers out there for maximizing quality on the various fabrics emerging in our market,” says Anderson. “But we’re called on to be more analytical than in the past. Every shop is different and approaches printing in its own way. What’s important is that you set your own standards and develop processes for monitoring your quality and addressing the printing issues presented by various garments.”

But even diligent testing and research doesn’t always provide an answer. “If a fabric proves difficult to print, explain the issue to your client and send him a sample for approval. Or make the decision to either deal with the situation or refuse the job.”

Read more on "Prepping for a Quality DTG Print" or explore our February/March 2016 issue.

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