Raster vs Vector: What Your Letterpress Printer Actually Needs.

close-up of polymer plate for letterpress printing.

When a file comes in the first thing I look at is what type of file it is and how it was made. A PDF or native Illustrator file from an Adobe program tells me we're probably starting from a good place. A Canva export tells me we need to have a conversation.

There are a few things I check immediately. Whether the text is outlined, the graphics are raster (aka bitmap) or vector and whether there are proper bleeds set up. These aren't arbitrary preferences, they're the difference between a job that runs cleanly and one that doesn't.

Raster and vector: what they are and why it matters

For wedding invitations the topic of raster vs vector simplifies into two categories.

Vector covers your type and your solid one color graphics. Vectors are mathematical points with no resolution, it is just as crisp at one inch as it would be at one hundred feet or one thousand feet. This is one of the reasons they covert well into plates.

The main problem we see is that unless you zoom in, raster and vector files can look identical on screen. Zoom into a raster file though and you'll see the pixels and a pixelated image is not suitable for making a plate. If a raster file comes in we'll reach out and ask for the correct vector version before anything moves forward.

Sometimes the file comes back saved as an SVG, which is typically a vector format, but the artwork inside is still raster. It looks like a vector file. It isn't. At this point we try to find a way to move forward, either by seeing if the file they have has a vector image (for example a monogram file they purchased some times includes both raster and vector) or we can attempt to convert. We do not recommend this for text. For simple graphics it's fine. For detailed work it's worth doing correctly from the start.

For things like watercolors and images with shading and gradients, these are not printed letterpress. They're flat printed separately and combined with the letterpress elements on the finished piece.

(Side note: although it is possible to make plates with raster images at high resolution, the quality is not something we recommend. You can also reproduce photographic images in polymer by converting to a halftone, think old newspapers, but that's a topic for another day.)

What makes a press ready file press ready?

A few things come up consistently enough that I'll just say them directly.

Outline your text. When text isn't outlined the file depends on fonts being installed on whatever system opens it, and in most cases I will not have your font so it won't show correctly. Outline the text and it becomes a fixed shape that looks the same everywhere.

Outline your strokes too. A stroke that isn't outlined can behave unexpectedly when the file is processed. Convert strokes to outlines before the file leaves your hands.

Know your minimum line thickness. Letterpress has physical limits that your screen doesn't. A very fine line could easily be washed of the polymer plate when it is being created. As a general rule nothing thinner than 0.35pt. When in doubt go a little heavier.

Put bitmaps on their own layer. If your design has watercolor artwork or any raster element put it on a clearly labeled separate layer. This lets me see exactly what I'm working with and handle it appropriately. A 600 DPI watercolor on its own layer is workable. The same file flattened into everything else is a problem.

Set up your bleeds. Any element that runs to the edge of the finished piece needs a bleed, 0.125 inches beyond the trim line on all sides. Without it the trim can leave a white edge where the color or design should go to the edge. It's a small thing that's very visible on the finished piece.

File formats we prefer

High quality print PDF or Illustrator PDF for most jobs. If you're in InDesign package the file so everything travels with it. If you're not sure whether your file is set up correctly send it anyway and I'll tell you what needs fixing. We have an Artist File Guide on the site that covers the specs for every job we run. Worth a read before you start building.

Ready to send your files? lollipopletterpress.com/lolli-press

-Tom, Lolli P