That is the question. And one that comes up a lot from our partners. When a customer selects an apparel SKU, they can select their print with or without an underbase. Sooo… what is underbase? Why would you need it? Are there rules you should follow when deciding? Well, glad you asked.
What is Underbase?
When printing on apparel, the fabric is not white by default and that’s where the underbase comes in. An underbase is a layer of ink (generally white or other light color) that is printed as a “base” on a dark shirt for other colors to sit on. This gives the top colors more brilliance. Think of it as a sort of “primer” to allow the other inks to pop with color on the shirts. Since the underbase is generally a high opacity ink, it is flash-cured before the top colors are printed over it.
Most vendors use the CMYK color model for DTG printing. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key (black). The underbase is the white color applied first, which acts as a barrier to keep your shirt color from bleeding through, mucking up your print colors.
You may be concerned that this layer of white will be visible in the final, finished product. However, when done properly the customer should not be able to see the underbase at all.
Why is Underbase Needed?
Underbasing is a very useful tool in the industry and at Gooten we consider it invaluable for printing light ink colors on darker shirt colors. If there is no underbase, white color won’t be printed at all, because no CMYK ink combination can produce white color.
Manufacturers use water-based inks in DTG printing, and the colors (CMYK) are translucent. To see the image at all, we must first apply a white base print and then add colors on top. This base print is the key to a bright and vibrant image. Get the underbase right, and the rest of the print naturally will fall into place.
When You Should Use It
Here are some general rules to follow when deciding to use underbase:
This is usually the primary reason to use an underbase. If your shirt color is anything other than white or a pastel, you will likely need an underbase. There are more colors that usually don’t need a white underbase (like sand and yellow haze), but if you’re estimating on your own, it’s best to include an underbase. Dark garments require a white underbase to be printed first because the shirt is darker than the colors in the artwork.
Ash and heather shirts are a bit of a “gray” area (hehe) when it comes to screen printing underbases. If you want a softer print, in most cases it is okay to opt out of the underbase on these t-shirt colors. Be aware, however, you are likely to see some of the darker flecks in the shirt showing through the ink. If the print color is bright, the gray will dull it down a little.
Ice gray, silver gray, and other flat gray colors that are on the light side are generally okay with no underbase. However, an underbase is probably needed for asphalt and charcoal t-shirt colors.
Two issues that can potentially influence an underbase are the fabric composition of the shirt and any seams that fall close to the print area. A variety of issues with the fabric type can affect the underbase – the amount of absorption that the fabric has, for example (and whether it will soak up or repel the ink) or how fuzzy the surface of the material is. An ironic thing about ultra-soft, treated shirts is that they tend to have finer fibers that stick up and feel softer, but also cause an underbase print to not release well or peel back up into the screen.
The more complex a design, the smaller the individual elements become, which can make creating a successful underbase more difficult. Designs with many different elements (shapes, spaces, lines, etc.) and/or a lot of color transitions usually require careful consideration. Although a simpler underbase can occasionally work with a complex design, usually it’s a sign of a poor-quality separation, where the underbase is too solid to properly support the detail in the top colors. It doesn’t have to be a nightmare, but it will be usually take considerably longer to prepare than the other colors in the design.
The placement of the design on the garment can become a concern when seams or the edge of the garment cause the squeegee or screen to become unlevel during the print stroke. This is a common problem when printing across the zipper of a hoodie or over the seam of a garment’s shoulder sleeve. These “bumps” push the screen away from the surface of the garment, causing distortion in the underbase that you’ll typically see as bleeding, puckering, or image drop-offs in the final print.
So did we miss anything? Let us know in the comments section if you have any other questions about underbasing that weren’t addressed. In the meantime, keep all of the above rules and ideas in mind and see your prints jump off the shirt!