Since the introduction of the first personal computer, we have ushered into the “digital age.” Technology has transformed virtually every aspect of our daily lives, and this phenomenon has been no different in the digital printing arena. Digital printing technology is pushing the envelope when it comes to what we can print on and how to do so more efficiently.
If you currently are in the apparel decoration industry (or contemplating a move toward it), you probably have an interest in the concept of digital printing, as it offers multiple options for easily bringing full-color printed apparel production into any shop. Digital decorating also is an ideal solution for small runs and on-demand printing, as the setup and production is quick and simple.
This brings us to another important point: the effect of garment color on image color. Without a doubt, the best garment color for any printing of any kind is white. As soon as you move into anything else, the image color may be degraded. Thus, there are challenges to printing on colored garments, especially dark ones. In DTG printing, one solution is to use a chemically engineered ink called, quite simply, “white ink.”
What’s White ink?
Part of the challenge of working with white ink is that it has titanium dioxide in it. It’s a unique pigment that, for years, has been used to create white inks of all sorts. In other words, it makes your white ink even whiter. To create the ink, we suspend this metal compound in water, and over time, it settles due to gravity.
When the ink settles, it has the potential for damage to the ink lines, dampers, capping station, and print head. So, to prevent that, you’ll need to agitate a cartridge, bottle, or utilize an auto-circulating system of some sort.
If your printer doesn’t circulate white ink for you, then you will need to make sure the ink stays in the solution by performing regular maintenance.
What’s the Function of the White Ink?
It has two functions in garment printing. One is a base coat for images on colored garments and the other is in the re-creation of the color white on colored garments.
Digital colors are combining different percentages of base colors (mixing). Unfortunately, the color white cannot be produced through any combination of colors; thus, white ink has to be engineered as a separate, stand-alone ink.
Because there is not a recipe for the color white, graphics programs typically leave any white areas in a design “open” under the assumption that they will be applied to a white surface. In that situation, the background color fills in the open area and creates the needed white. But if the same image was applied to a blue shirt, the supposed white areas would now be blue, which may not be ideal. With a white ink system, a command is sent to the printer telling it to apply the white ink (from an independent cartridge) when required, thus making it possible to print the color white.
The second aspect of white ink is the creation of base coats. With digital printing, you are applying a thin coating of ink or dye — meaning the colors of the ink will be intertwined with the colors of the fibers, which may affect the image color. To counter this effect, you can apply a base layer of white ink, which blocks out the background color, such that the image is actually being applied to a white background instead of directly against the color of the garment. The process sounds easy enough, but there is a lot more to this.
How to Correctly Use it?
White ink has to be thick enough to create a decent base, yet thin enough to get through the inkjet nozzle. In addition, it has to cure quickly so that other inks can be applied on top of it without any quality issues. Chemically, it must start “drying” as soon it hits the surface of the garment.
This is accomplished by a two-pronged approach. The first is that the white ink itself must be engineered to cure quickly. The second is that a secondary chemical called a pre-treatment typically is added to the surface of the shirt before printing. When the white ink contacts the pre-treatment, the curing time is accelerated such that the production proceeds uninterrupted. This means there’s no need to stop and wait for drying to occur.
Early white ink systems developed a reputation for clogging and drying out in the print heads, which led to expensive repairs. New advances in technology have greatly improved the process and — for the most part — if you fully understand how your system works and follow the instructions provided by the manufacturer, you shouldn’t experience significant problems.
In reality, white ink is not needed on every job; thus, not all DTG printers offer it. But before you insist on having white ink capabilities, make sure you balance your desire against your need. White ink does present challenges, one of which is the artwork that has to be prepared differently to accommodate white ink. So know what you are getting into, especially since it typically raises the price tag in addition to the level of production complexity.
What about the ink for sublimation? It’s not available. There are some alternative methods, such as allover sublimation where you apply an image that completely covers the surface of a shirt. You start with a white shirt and then recolor it while adding graphics all in one step (per side). It requires a wide-format printer and heat press but is gaining in popularity for creating retail-inspired looks for a multitude of market niches.
