Digital Decorating: Process + Techniques

---

May 20, 2015

“There’s something wrong with the ink.” “There’s something wrong with the printer.” “There’s something wrong with…” a hundred of other reasons direct-to-garment (DTG) prints look dull, stiff or otherwise imperfect. Those of us in the world of DTG printing hear similar statements nearly every day. As with all things garment decorating, the first thing we hear is, “It’s the ink, or the machine, or…” you get the idea. It’s never me. It’s never something I’ve done.

In the case of DTG printing, there is nearly always another reason for a less-than-perfect image on your garment rather than either the ink or the machine. For the purpose of this article, we’ll assume we’ve started with a high-resolution, well-prepared piece of artwork (a dream job that is subject for another article). If the image looks perfect on one garment but not the next, our search for an answer will go beyond the ink or the machine.

PRETREATING
Just as with other garment decorating methods, dark fabric DTG printing is where the complications and level of expertise reveal themselves. Based on personal experience with countless end users, pretreating is the singular area of confusion and cause of poor printing results.

Too little pretreatment will provide a dull image. Pretreatment provides a barrier for the water-based ink to set upon as curing begins. An application of too little pretreatment, and the ink will absorb into the fabric and appear dull or washed out.

On the other extreme, too much pretreatment will cause difficulties as well. As with many things, the assumption can exist that, “Some is good, therefore more must be better!” This is not at all true with DTG preparation for printing.

Too much pretreat will result in a stiff feel on the shirt. This is the square or box that some complain of with the assumption that it is an unavoidable consequence of the process. In fact, this stiff square is caused by too much pretreatment applied to the shirt, and is by no means the “nature of the beast” as it were when choosing the direct-to-garment process of decoration.

A step further, more pretreatment may have a more dire result. If the ink does not bond to the fabric because of a heavy layer of pretreat solution, then the image may wash off the garment — the ink is printed on top of a heavy barrier of pretreatment and not actually in contact with the fabric of the garment. Many decorators will attribute this washout problem to either the ink or the curing process. But, if the image washes off the shirt, it is more than likely the result of too much pretreatment than any other cause.

There are a few choices when it comes to application of pretreatment, but the most commonly accepted methods as of today are hand spraying with a power paint sprayer, or by using an automatic pretreat machine. First, you can achieve the same result using either method, but more application errors occur using one method over the other.

Using an automatic pretreatment machine will give you consistency from shirt-to-shirt. Which means, once you’ve dialed in your ideal spray time/lay down amount, you have repeatability. Plus, if the machine is enclosed, you can operate it near your direct-to-garment printer.

Hand spraying can achieve the exact results, but it takes some additional time practicing to achieve an even spray across the garment. There is a tendency to spray just a little bit more when hand spraying. In addition, hand spraying can be messy (sticky walls and floors), have inconsistent application, and cannot under any circumstances be performed near your machine.

Ideally, this hand spraying function is accomplished in a separate room. If more than one person in your shop pretreats shirts with a hand-held sprayer, you will be able to see inconsistency between prints depending on who sprayed the pretreatment solution, just like your own pretreatment fingerprint.

THE GARMENT
When faced with an image-quality issue, the second question you’ll be asked by the machine support staff on the phone will be, “What brand of garment are you printing?” This is a surprising truth for decorators who are already screen printing or using some other form of garment decoration. For most printing and graphic applications, the garment selection has little impact upon the finished print. This is not true for DTG printing.

Since we are printing a water-based CMYK + white ink system through a very fine inkjet print head, the substrate we are printing on will define the quality of the final graphic. No amount of switching out pretreat solution, varying the amount of pretreatment applied, or manipulating the quantity of white ink laid down as an underbase will fix this problem. In the end, the truth is “not all garments are created equal.”

Of further frustration, many of the traditionally standard garments used in other decoration methods do not measure up to the requirements of a quality finished direct-to-garment print. Translation: Just because it’s on sale does not mean it will work well with your DTG system. Some of your favorite and well-known industry brands will not produce an acceptable result for you.

There is good news here, too. With the proliferation of direct-to-garment printing, we are now discovering which garments work best. Second, more manufacturers are addressing the need for specific garments for this decoration method. Further good news is that these garments specifically made for our process are similarly priced to the garments you are already using for other applications.

In direct-to-garment printing, 100% cotton garments are the absolute best substrate. This is true of all machines across the spectrum of manufacture and price. While we can get away with the lower end of garment quality with most other decoration methods, DTG will require you to buy better-quality garments for an acceptable and salable end result.

Can I print blends, down to a 50% cotton/50% polyester? Yes, but the result will not be as bright and will not wash quite as well as 100% cotton. If you’re comparing a print on 100% cotton with a 50/50, the blended fabric print will never be as bright and crisp as 100% cotton.

When selecting the right garment for printing, the first choice always will be a ring-spun, combed cotton. You’re looking for a tight weave and a smooth surface for printing. Very fine detail can be achieved in direct-to-garment printing, and a smooth surface will allow for that detail to be better seen.

What about crew-neck and hoodie sweat shirts? It is difficult to find 100% cotton fleece material in a wide range of colors. But, printing higher cotton blends such as 90% cotton/10% polyester, or 80% cotton/20% polyester, will result in a perfectly acceptable finished product. The key to printing on blends is that the higher the cotton content, the better your finished image on that garment will appear.

ENVIRONMENT
While environment is the most critical factor in the health of your direct-to-garment printer, it has the least impact on the image you are producing from garment to garment. In other words, when I print one garment and it looks perfectly fine, but the next garment isn’t ideal, the cause isn’t typically the environment.

Yes, if it is too cold in your shop the ink can become sluggish and be the cause of “ink starvation” or not enough lay down on the garment; too hot and the ink may start to dry in the print head. But the environment (normal office temperature and around 50% humidity) is rarely the cause of poor image quality when comparing one garment to next.

The pretreat application and garment selection is nearly always the root cause of irregular print quality. This is true of all direct-to-garment printers on the market today. Choose the right garments when printing with your DTG machine. Find the perfect range of pretreatment spray application for the garment. And, as with all things garment decorating, allow for testing, testing, testing to find the perfect combination of garment and pretreatment.

Terry Combs is a more than 35-year veteran of the garment printing industry, and has managed production shops large and small across the United States. He is currently in sales and training with Equipment Zone, Franklin Lakes, N.J. For more information, visit terrycombs.com.