Understanding Halftones and Screened Plates

Understanding Halftones and Screened Plates for Letterpress Printing

When a fellow printer sent us a plate they'd mistakenly ordered at less than 100% opacity—and ended up with tiny dots instead of solids—we realized it was the perfect opportunity to dig into a technique many letterpress printers have heard of, but few have explored deeply: halftone printing. So we called in the experts, Shelley and Max Otto of Concord Engraving, to explain everything we ever wanted to know (and plenty we didn’t know to ask) about halftones and screened plates.

What Are Halftones and Screened Plates?

Halftone printing uses tiny dots to simulate varying shades of color. If you’ve ever sent artwork to be made into a plate and accidentally left some elements at less than 100% black, you’ve likely discovered this the hard way—your plate comes back dotted, not solid. But when used intentionally, this technique is incredibly powerful for creating tonal variation, especially in one-color jobs.

Screened plates are created from rasterized images—meaning the artwork is broken into a pixel grid, not smooth vector lines. The process is managed through something called “raster image processing” or RIP, and it’s handled entirely on the front end before a plate is even made. At Concord Engraving, that means turning your PDF into a high-resolution file (at 4,000 DPI!) where each tone is translated into a specific dot pattern.

File Prep: What You Need to Know

The most important step in halftone printing happens before the file ever leaves your hands. Shelley emphasized that you must work in grayscale (or at least one solid color) and avoid sending in files with multiple colors or complex CMYK profiles—unless you’re intentionally printing in process color. Keeping it simple from the start makes a huge difference in how the final piece prints.

One major mistake designers make? Setting color percentages too close together. Because of dot gain (more on that below), percentages like 80%, 90%, and 100% will often look identical once printed. Instead, aim for noticeable contrast—45% to 70%, or 30% to 60%—so the variation holds up on press.

What Is Dot Gain?

Dot gain is the phenomenon where printed dots appear larger than they are on your screen, due to pressure, paper absorbency, and ink spread. On a letterpress, this is especially significant. Max explained that halftones often gain 10–15% in coverage once ink hits paper, which is why Concord can apply a tonal “curve” to your file to compensate.

This curve reduces dot size in your artwork so that it expands into the desired size on press. That means if your darkest value is 60%, it might print like 70%—so they prep for that accordingly.

Should You Do the Screening Yourself?

Short answer: no. Shelley and Max made it clear—let the pros do it.

While you can manually apply halftone patterns in Photoshop, shrinking or resizing the image after screening can cause problems. Most common mistake? Setting a line screen (say, 100 lines per inch) and then scaling down the image—causing that value to skyrocket and rendering the print unworkable.

Leave the screening to Concord. Their RIP software automatically assigns proper angles for overlapping colors (important for avoiding messed up, rippled patterns) and ensures consistent dot sizes based on your plate material and print specs.

TLDR: your plate-maker knows what they’re doing! Let them handle it.

Best Use Cases: Watercolor, Photos, and Color Overlays

Some of the most beautiful halftone applications are subtle. Watercolor textures and photographic images translate especially well with screened plates—giving that soft, tonal depth that would otherwise require multiple color passes. Even simple overlapping color bands can take on rich, blended effects with this approach.

Want to print a grayscale photo of your grandmother? Just send the photo. Concord can handle the scanning, the DPI adjustments, and the screening. The same goes for hand-drawn illustrations or lightly colored textures.

Overlays are another amazing use case. When you print multiple halftone layers with transparent inks, they can blend into entirely new hues—expanding your color palette without needing more ink on your shelf.

Plate Materials and Lines Per Inch (LPI)

Not all plates are equal when it comes to screening. Concord recommends standard photopolymer plates with a thinner relief (.95mm), as they’re more stable and hold fine dots better than deeper relief options. That’s especially helpful in those highlight areas where tiny dots might otherwise collapse or wash out.

They generally screen at 100 LPI for letterpress, though they can go up to 110 or more if needed. Higher LPI = smaller dots, which equals finer detail—but also more risk of muddiness and dot gain. For most printers and presses, 100 LPI offers the best balance between clarity and ease of use.

Save Time and Color: Use Halftones Strategically

Max shared one of the most practical takeaways of the episode: screened plates can save time on press and help you stretch a single ink color into multiple shades.

Want to simulate a full floral illustration with depth and dimension but only have one ink color? They can screen that artwork and apply curves that create lighter midtones and shadows—all on one plate.

Better still, you can ask Concord to create tonal test plates with your favorite inks. That way, you’ll know exactly what 10%, 40%, and 70% look like in dusty rose or navy blue—making design decisions that much easier down the line.

File Tips: How to Send Halftone Projects

If you’re designing something with layers, gradients, or photo-based imagery, your best move is to send the flattened grayscale artwork directly to Concord and let them handle the screening. Want to overlay multiple colors? Send a composite image with Pantone assignments, and they’ll separate and screen each plate accordingly.

This approach helps avoid issues with tiny dots that are too small to hold on press—or misaligned screens that cause uneven color or moiré. Their software is built to handle this with precision, and they’re always open to reviewing your file before production.

How to Clean and Store Screened Plates

Screened plates require a bit of extra care, especially in cleaning. Because the dot pattern creates tiny wells, ink can get trapped easily—so be thorough, but gentle. Don’t leave them sitting with ink overnight, and avoid hard scrubbing that might remove delicate highlight areas.

For storage, keep your plates sealed in a bag with the protective plastic, just like any other photopolymer. Shelley mentioned she still has test plates from the 2019 National Stationery Show that look brand new—proof that if you take care of them, they’ll last.

Yes, You Can Recycle Plates

Concord confirmed that most plate materials—once the sticky backing is removed—can be recycled like a plastic bottle. While this may vary by state, in New Hampshire, Shelley confirmed their recycling center accepts them with no issues. So if your pile of unused plates is growing, check with your local facility. There’s a good chance they’ll accept them.

Final Thoughts

This episode cracked open a whole new world of creative possibilities. We’ve both known about halftones for years but never fully understood how accessible they are—and how much help is available when you work with an experienced plate vendor like Concord.

The idea that you can send a scanned photo or painted texture and let Shelley and Max take care of the hard part? It changes everything. From simpler overlays to complex CMYK-inspired prints, screened plates are a game changer for any letterpress printer ready to expand their range.

So go ahead—design that watercolor print. Halftones (And Concord Engraving!) have your back.