5 DTG Pretreating Secrets Every Apparel Decorator Should Know

THE KEY COMPONENT of printing on a direct-to-garment (DTG) printer isn’t the printer, or the artwork, or the curing. It’s the pretreating step in the process. This part of the DTG equation is the basis of a quality finished product and not enough attention is given to this pretreating step. Let’s talk about the five pretreating secrets of DTG success.

Using an automatic pretreat machine will give you consistency from shirt to shirt.

The Importance of Proper Pretreating

Each step in the DTG process builds upon the one before it. Get the shirts pretreated properly, and you’re on the way. So, what are we accomplishing with an application of pretreat before printing? Pretreating gives us a base for our inks. Much like the flash-cure step in screen printing after you print a white underbase, pretreatment causes the white underbase to start to cure from the bottom up.

The resulting base determines the brightness of the finished print. Done properly, you get a screen print like finished product, and fabric that isn’t stiff where the pretreatment was sprayed.

The secret ingredient basically is salt water. Yes, there are binders, etc., that make your pretreatment work with your ink system. But an invisible layer of salt on the shirt is the magic. Salt combined with the water in the water-based ink causes the flash-drying effect to happen from the bottom of the ink layer and up.

A properly pretreated shirt will render bold, bright prints.

Let’s Talk Fabrics

It’s become a common understanding that 100% cotton shirts are the best friend of DTG decorators. But not any cotton shirt will do. Your “very” best friend as a DTG decorator is a ring-spun cotton shirt. Many blank goods purchasers don’t know that ring-spun cotton uses thinner threads than regular cotton garments. That translates to a tighter weave and a smoother surface to print upon. The resulting finished printed shirt is bright, crisp, and is exactly what our customer is hoping to see.

What does this have to do with pretreating? A tight, smooth weave fabric will take less pretreatment to render a bright, crisp, finished image on the shirt. Less pretreat on the shirt results in a softer feel to the fabric around the image and makes a better presentation to your customer. And less pretreat saves you money in the overall cost to produce the finished product.

Pros/Cons of Pretreating Whites

Is there really a debate on whether you should pretreat white shirt or not? It’s not so much of a debate as what it is you want and need to accomplish.

First, unlike color shirts that you must pretreat, white shirts printing just CMYK inks offer you the option of pretreating, or not to pretreat. In my opinion, it’s personal preference and the audience you’re serving.

For most decorators, an image on a non-pretreated white shirt is perfectly acceptable. What does pretreating add? The image will be a little brighter, the colors a little more true and you’ll get a little better washability. The question is, what does your customer or your marketplace expect? In my experience, more DTG decorators do not pretreat a white shirt, than do.

Also, some pretreats can yellow in the sun before the first wash. So if these shirts are going on a six-year-old kid’s soccer team, skip the pretreating.

For the best results, heat press for five seconds or so before you print a stored pretreated shirt or an already-pretreated shirt from your wholesaler.

Commercially Pretreated Shirts

“This print just doesn’t pop. I know it’s not the shirt. I bought it pretreated from my wholesaler. What am I doing wrong?!”

I read that on a DTG forum this year. Maybe not word-for-word to protect the innocent. There was a time in my garment-decorating journey when I might have made the same assumption and said something very similar. “It can’t be the shirt. It’s got to be me, right?” Let’s not be so hasty.

DTG printing is only about 20 years old. I’ve been lucky enough to have been a part of it all from Day One. As to already-pretreated shirts, there have been multiple attempts over the years. Early on, they were not so good. But as with all endeavors, each iteration has its improvements.

Are we there yet? In some ways, yes. Many already-pretreated shirts print beautifully. But still, some print better than others. I’m certainly not saying to avoid this product. I am saying don’t blame yourself immediately if prints aren’t what you would expect. Experiment with every style and color you want to decorate. And always test by printing the same graphic on a shirt that you know has ideal pretreatment application. We’ll only get better from here. Just don’t be so quick to blame yourself.

Pretreating a white T-shirt before printing is a personal preference. Pretreating, though, will give you a crisper image, more true color matching, and better washability.

Shelf Life Strife

Clearly, since pretreated shirts are available for purchase from T-shirt wholesalers, there’s some level of shelf life. Why does that matter to a decorator who does their own pretreating as needed? Because during production downtime, staff can be pretreating shirts rather than standing around or being sent home without pay.

If you pretreat ahead, it’s better to store those shirts in a cool, dark place. Putting them back in the box they came in is fine. The key is what you do when you’re ready to print. After pulling a shirt out of storage, you will find the fibers on the surface have been pulled up because of the contact with the shirt on top. That causes a rougher texture in the print. And, if you have any humidity in your shop, the shirt will have absorbed moisture.

The solution is simple. Just before printing, heat press the shirt for about five seconds. That resolves both issues, and your shirt will react as if you just pretreated and dried it.

But how long can you store them? On the internet, I’ve seen everything from “print the same day” or “print within two weeks” and beyond. Those recommendations are baseless.

Here’s an actual example from real life. Brian Walker with Image Armor Preatreat actually tested this. He pretreated 12 shirts and then printed the same image on the same DTG printer every month for a year. Each print from the day one print to the 12th month print looked exactly the same.

I won’t say the shelf life is forever, but it’s a very long time. Brian shared that he recently printed on shirts that were pretreated in 2016. The key is to press just before you print to lay down the shirt fibers and drive off any moisture in the garment.
  
Here’s a pro tip to wrap up: Most decorators use too much pretreat solution. Back off the amount and test. Then back off the amount and test again to find your true sweet spot of pretreat application.