Underbase in screen printing is crucial to the final result in terms of precision and opacity. Choosing the right technique of application is important, as depending on your print you might want to apply a different color, use a different screen mesh, or perhaps not use an underbase at all. Understanding the idea of the base and comprehending how it contributes to the outcome can make you improve the quality of the prints with less effort. In this article, we explain how different kinds of under bases can influence your projects.
Probably the most popular and versatile approach is applying a white underbase on your shirts. Then, the biggest problem is selecting the proper screen mesh. A relatively lower screen mesh count should always be used not to apply too many layers of ink.
Choosing the right mesh count
The recommended count is somewhere between 110 threads/inch and 160.
Lower mesh than 110 is rarely used in general, almost exclusively for special inks, like glitter. There’s a risk that the garment would not absorb the ink properly if you use a screen with mesh lower than 110. Also, the ink has to dry out well before applying the next layer. A higher screen mesh than 160 can result in dull color, which might require putting up the next layer. Therefore, you might end up with a thick plastic-feeling coating. Not always you want to go for full-opacity white. Although you want to make your underbase consistent. Think of it more as a support for the ink you’re going to put on top of it. If you put too many layers or a too thick layer of ink, the coating might end up being stiff as a plate. Higher screen mesh is recommended if we are using a machine press due to the higher pressure being put on the screen than when you are applying the ink manually. For manual use, 110-150 is completely fine. However, the mesh itself is not the only factor making the underbase more/less opaque.
Same color underbase
In some cases, it’s worth considering using the same color for the underbase often explained as a hit-flash-hit technique. Especially if you are screen printing one-color graphic like for example text or geometric shapes. It’s helpful when it comes to the positioning of the print on the shirt and takes less time making you achieve the same quality as if you were using a white base with less effort. Moreover, it can also improve the texture of the print leaving the garment remarkably softer. Applying an underlay of another color than white is also rarely used in some more rich graphics where a light or pastel color can be used as a background color as it’s disadvised to use too many layers of ink on garments.
In some cases, it’s alright for the shirt color to penetrate the print, like in a vintage design or when you’re looking for a washed-out appearance. This kind of print will paradoxically keep its condition for a long time as screen prints this light, don’t tend to break. This technique is reserved for experienced printers or semi-automatic and automatic screen printing machines, as it requires a very even tension for the ink to pass through the mesh and is most recommended on good-quality garments. Another situation when an underlay doesn’t have to be used is having a white or a very bright pastel color garment to print on. It needs an underbase only if the colors you are using are very bright too, like for example light pink on pastel turquoise, or when you have a very complex design to pull off.
Background as underbase
Every time you’re applying the underlay remember that if you also have some white elements in the project you should think of it as a part of the underlay, as you will have those white elements merged with the underlay in the process of color separation, and therefore most likely go for higher opacity of the underbase. In this case, a thicker mesh is not recommended.
Other approaches to underbase
Although it’s possible to print white background and underbase at once, sometimes the top white is separated in simulated process color separations regarding halftones. It also happens that screen printers successfully experiment with different whites or colored underbase. It’s considered, for example, when the project is rich in various colors and we just lack enough heads, or when we are making the base for glitter inks, or we’re about to darken or saturate specific colors on the print. The problem is the difficulty to preview the effect accurately without physically applying it to the garment.
The garment itself has its ink capacity, which needs to be taken into consideration while choosing the perfect screen. The thicker is the ink, the harder it is for the fabric to absorb it to the core. Especially for the high-weight or soft treated shirts. It influences the underbase opacity, making it harder to find the sweet spot between a stiff print and a worn-out look. That’s why it’s strongly recommended to make test prints. It’s a good idea to get some garment samples and experiment before you start the actual production. In this case, experience helps a lot and makes it possible to rely on your intuition up to some point.
Preparation is the key
Generally, the more a design gains on complexity, the smaller the individual elements become, making it more difficult to create a successful underbase. The cohesion of what we see on a computer screen (even after separating the colors) and what we see on a garment will depend a lot on the quality of an underbase, being a canvas for our further works. It can be too thick, too transparent, sloppy, uneven because of either, application or absorption. Some of those issues can be eliminated in a process of the right color separation, and some just require an experienced hand and good tools. But it’s not supposed to be a nightmare at all. It can be a subject to a lot of productive experiments, and it just needs decent preparation. After all, it’s the primary layer applied on a shirt.