Many times white ink DTG users complain that their printed whites just don’t look like what they saw at a trade show. “It just isn’t white enough and we are doing exactly the same artwork and everything – it must be something wrong with the printer or pretreatment machine!”. There are many factors that can affect the final output of a digitally printed shirt. One of the biggest is the one you probably wouldn’t think of first.
Pretreating does two basic functions for the digital printing process. The first is that pretreatment process is similar to the process of applying primer to drywall. You apply primer to drywall so the paint doesn’t soak in, and the pretreatment primers the T-Shirt for the same function.
The second function is that once the white ink is printed onto the pretreated shirt the white ink reacts with the pretreatment and it changes “state”. You can think of this state change like the flashing of white ink in screen printing. A white underbase is flashed in screen printing utilizing a heat source so that you can print a solid color on top of it so that the inks don’t “mix” and you get a crisp, clean image. When the white ink hits the pretreated shirt, the pretreatment “flashes” through a chemical reaction with the white ink allowing the CMYK that will be printed to do so on a semi-solid surface. This allows for incredible detail and no messy or blurry wet-on-wet printing.
However, when you utilize the same pretreating process, the same printing parameters and same artwork you can still get amazingly different results on your shirts. As can be seen in the photo to the left, there is a significant difference in the optical brightness and opacity of the printed garment. The only difference between the left side and the right side, and most often overlooked variable, was the brand and type of shirt printed.
The quality of the shirt is one of the biggest factors you can change to increase the quality of your finished prints. As can be seen in our illustration, the left side was printed with a Fruit of the Loom Heavy Cotton T-shirt while the right side was printed with a 100% cotton Keya brand shirt.
The tighter the weave of the shirt, the less rogue fibers straying from the thread, the better your final print (read ring-spun cotton). You can think of it as the difference between printing on regular copy paper and printing on photo quality paper off the same printer. The copy paper will print acceptably but the smoother photo quality paper will print much better. Though both printed off the same printer and pretreated the same exact way, the “photo paper quality” t-shirt will produce a much better, higher quality print.
So, the next time you are having issues with your white ink DTG prints and you want to blame the printer or the pretreatment machine, or the dog – remember to check all the variables. Utilizing the highest quality shirt, though costing a just a little more than your standard shirt you might be using, will yield up much better finished prints and more satisfied customers in the long run.