Customers are sometimes confused by the screen printing process. Years of practice have led to apparently unintuitive practices to create the best screen printed shirts. Techniques like applying a white underbase for prints seem odd at first, but after you take a brief look at the process, it starts to make a lot more sense.
Let’s start by imagining a scenario where you want a print containing bright colors printed onto a dark shirt. It’s probably tempting to start printing those bright colors directly to the shirt. The results will be pretty disappointing.
The opacity of plastisol ink ensures that the substrate color influences the appearance of the ink. For example, red ink on a black shirt is darkened by the fabric color that comes through the ink. This leads to a muted, drab design that inspires….well, it doesn’t inspire much of anything.
To get around that, screen printers apply an underbase of white plastisol, stuff with names like PAFC-1020 Fast Flash White. This layer of white gets a flash cure drying treatment, so it’s at least cured enough to print on. Then, the layers of your image are printed over that.
After all is said and done, the design itself will have rich color and sharp definition, because it was printed onto a white base. This is classic protocol in the visual arts, and is used to make the best possible custom print for you.
In a situation where you want white printed on dark colors, a similar, but slightly different process is used.
A single layer of white on black doesn’t have the vibrant appearance that you want from a shirt. The white is transparent on the first pass through, and allows some of the black or dark color to show through. To make the image stand out, it’s necessary to print the image twice. Between prints, the first layer is flash cured, like our first scenario.
There is another method for printing white to darks, which some printers favor. They prefer to skip the flash cure and just apply two coats, each at different pressures. At first glance, there is a difference between these two approaches. When using the flash cure, the coverage is more even and the print has greater definition. This second method does produce a nice, glossy plastisol texture, but the coverage is spottier. DFC uses the flash cure method for the best results.
Some people wonder if it’s possible to cut the corners on these print jobs. Of course it is, but in that case, why would you go to a professional print shop? Professional screen printers use this technique for a reason: quality. Without a white underbase, your print quickly fades, and the life of your shirt is reduced. The price of printing well the first time is realized throughout the life of the shirt. If you see a print shop advertising low prices because they don’t use underbase, you should suspect sub par shirts.