Digital graphics come in two varieties, vector and raster. Vector graphics are built with mathematical formulas, typically using Adobe Illustrator or CorelDRAW. Raster graphics, like those designed in Adobe Photoshop, are built from individual pixels. The big benefit of designing with vectors is that you can scale up or down most artwork virtually infinitely with no loss in quality, or pixelation. Raster images cannot be blown up without sacrificing quality. While you can still screen print using raster images of sufficient resolution, vector images are more versatile and ensure high resolution artwork. With a vector image, you can successfully print your design on anything from a t-shirt to a large banner with the same quality for each project.
So how do you recognize a vector image if you’re not the one who originally created it? Some common vector file formats include:
Note PDF and EPS files can be vector or raster. An easy way to tell the difference is to zoom in very close on the image. If it stays smooth at high magnification, it’s likely a vector image. You can also tell by opening the file in Illustrator and choosing Outline from the View menu. If you can see the image outline, it’s a vector. (For more info on handling customer-supplied art, check out this blog post)
Besides scalability, another benefit of vector graphics is that often result in smaller file sizes than raster files, because vector files do not have to store information about each individual pixel. This makes it easier to share vector files from computer to computer. There are libraries of vector clipart available for purchase to help you save time and streamline the art creation process in your screen printing shop. This can be a good solution if your shop doesn’t have a dedicated art department and you find yourself spending too much time creating art at the expense of other tasks.
If you have to work with raster images, make sure to design them in high resolution – 300 dots per inch (DPI) is recommended. It’s a good idea to design your raster images larger than you actually need. It’s easier to scale the image down without losing quality than it is to enlarge it without causing problems. Even vector images should be prepared at or near the actual print size; while they are much better suited to resizing than raster images, they are not always completely immune from issues.
As with any other aspect of the screen printing process, the best way to ensure a successful print is to practice! There are so many variables that go into designing good screen printing art, there’s no substitute for experience. With time you’ll develop a solid understanding of the art requirements necessary for a quality print and be able to design or manipulate accordingly every time.
For more tips to take the hassle out of screen printing artwork, check out these blogs: