Close up of pretreated and non-pretreated 100 cotton shirt

The Benefits of Pretreating

Brian Walker started in the screen printing industry in the mid-1980s while still in high school and has since been involved extensively with the direct-to-garment printing market. Currently, he is the CEO and owner of RTP Apparel and Image Armor. RTP Apparel provides pretreated T-shirts to the DTG industry. Image Armor is a DTG solutions provider that manufactures inks and pretreatments.

Direct-to-garment printing is sexy. Pretreating, however, is an unsexy yet necessary evil for printing white ink. Despite its unattractive reputation, pretreating helps white ink adhere and gel on a shirt while creating an underbase for the additional ink layers. Pretreating also aids in the ink’s wash durability through repeated cycles.

Still, most direct-to-garment users don’t pretreat white or light-colored garments that don’t require white ink. This is completely normal as most ink sets are designed to adhere to and work best with 100 percent cotton, alleviating any need to pretreat. That’s because pretreatment is only for white ink printing, right? Not so fast.


For a better overall business, improve your products. Happy customers are returning customers who continue to spend money with you. To keep these customers happy, you must give them the best possible products at reasonable prices. If a customer’s printed shirt doesn’t look good or degrades after the first wash or two, you’ve defeated the primary objective of customer retention.

All shirts are not created equal, and there are hundreds of available brands and styles. What’s a decorator to do? First, find a high-quality ring-spun cotton shirt with a tight weave. A tightly woven shirt with a high thread count generally has fewer holes and provides a greater surface area for depositing ink. The same design printed on a loosely woven shirt looks lighter in terms of color saturation than a tightly woven fabric. Remember, you can’t print on air, and water-based inks do not bridge the shirt’s weave like traditional screen printing.

Water-based inks are designed to print directly onto 100 percent cotton and heat set to create a durable, wash-fast product. In general, this produces a sellable product but often results in a flat, dull print. Many direct-to-garment decorators ramp up the print’s vibrancy and quality through RIP software while some turn to double printing. However, these pseudo solutions increase the ink cost, and in the case of double printing, it usually takes twice as long to print, resulting in more labor and overhead expenses on a per-shirt basis.

Even though pretreating every shirt may cost slightly more in materials and labor, the savings is generally greater or about equal. In addition, that more durable, vibrant pretreated print has a higher impact and perceived value to your customers when they open the box and look at their printed shirts. Never underestimate the “wow” factor.


In Figure 1, at the top of this article, the printed shirt is high-quality ring-spun 100 percent cotton. We pretreated the right half of the garment and kept the left side in its natural state, which allowed us to more easily see the differences that pretreating made. The left side is much less vibrant than the pretreated right side as it allows the ink to soak into the pretreatment rather than the fabric’s fibers.

In the close up of the black area in Figure 2, at left, there is a definite vibrancy and color intensity between the pretreated and untreated sides. The pretreated black holds a deep hue while the untreated side looks grayer.

In addition to the increased color intensity, pretreating improves the print’s detail. When ink is printed onto an untreated garment, it tends to spread from the point of impact. Naturally, cotton is absorbent, and there’s some inherent spread of the ink, commonly referred to in screen printing as dot gain.

However, when ink is printed onto fibers of a pretreated garment, it tends to stack up and not feather into the surrounding fabric. The pretreatment acts as a base to hold the ink in place, creating a more detailed image and better-looking garment. This is most notable on fabrics that wick moisture more than cotton, such as polyester.

Today’s high-performance polyester fabrics wick away moisture from the skin. This is great if you’re working out but bad when you’re trying to print onto polyester with a direct-to-garment printer. As soon as the ink hits the shirt, it wicks away from the point of impact, causing the image to blur and weaken in color intensity, as can be seen in Figure 3, at right.

However, the inset on Figure 3 shows the detail and vibrancy of the same 100 percent polyester shirt with a pretreatment. The image clarity and vibrancy are as different as night and day. You can even achieve the look of sublimation on 100 percent polyester when using the right pretreatment with standard water-based inks. Printing on 100 percent polyester can open entirely new sales areas for your direct-to-garment printing business.

A pretreatment designed to work specifically with white ink generally doesn’t hold CMYK prints unless there’s a white ink underbase. Otherwise, the print may look great before washing but then experience poor wash fastness and image degradation.

Many argue that pretreating a garment with no white ink is a waste of time and money. I would argue that correctly pretreating every shirt opens doors of opportunity and profits that have not been realized. Not only will the standard, run-of-the-mill white shirt with a full-color print look better and fetch a higher price but printing on other fabrics, such as polyester, is now possible. This gives you and your customers additional decorating options with direct-to-garment printing as well as higher profit possibilities for your business.