Tag: Risograph Printing

Troubleshooting

Common Questions

If I want to switch out the color of a plate (print on a blue plate using the teal drum), do I need to alter and re-save my file?

No. The printer reads your plate as a grayscale file and prints in whatever color is loaded into the machine.

Is this the only way to save a Photoshop file?

No. There are a lot of ways to prepare a Photoshop file. You are welcome to research and use other methods on your own.

Troubleshooting

I can’t add a new adjustment layer to my file

Once you add spot colors and/or switch to Multichannel mode, you cannot add any more adjustment layers. However, you can make channel adjustments using Image > Adjustments > Levels (or Curves).

If you want to make major adjustments to your file, go back to CMYK or RGB mode and make the adjustments. Note that this will delete the spot colors that you’ve already made. But if you are making drastic changes, it is better to do so in CMYK or RGB. After you’ve made your changes, repeat your preferred process of color separation.

The Multichannel or CMYK mode is grayed out

Some of the color modes won’t convert between each other. You may need to switch to grayscale first, and then switch to your chosen color mode. Grayscale will discard color information, so you will need to re-color if you use it as an in-between mode.

Tips

Double-sided printing tips

There will always be roller marks when double-siding. But they can be minimal if you take the following steps

  • Print the side with the least amount of ink coverage first.
  • Bring back your opacity to 80% across the board.
  • Roller marks tend to appear towards the top and center of the page. The more ink in that area, the more prevalent the roller marks.

Interactive Pieces

Anything that is being handled a lot (like a flipbook or resume) should be at 80% max.

Color Systems & Color Spaces

Understanding RGB vs. CMYK vs. CMY

The primary colors of light RGB (Red, Green, and Blue), represent a visual range that, in theory, can produce any color that can be seen by the human eye. Mixing with light is an additive process. (When you add all the colors together, they make white.)

Printing is a subtractive color process and uses the opposite colors, CMY (Cyan, Magenta, and Yellow) to mix and produce an image. Working with physical colors (i.e. dyes, pigments, inks) brings with it the limitations of your materials. In theory, cyan, magenta and yellow, all together should produce black. But in reality, the pigment usually turns to a muddy, inconsistent brownish-black. (The shade of brownish-black is dependent on your materials.)

This is why Black (or K for Key) is added in addition to the CMY gray-blend, giving you a sharper, richer, darker black.

So, when you are printing in CMYK, about half of your grays and blacks are made with an even blend of CMY, and the other half is a layer of black printed on top. In theory, all of your CMY channels should have the same information as your black channels, just at a lighter value.

Overall, subtractive color spaces tend to have a wider spectrum of colors to offer. This is why most people work in an RGB color space such as Adobe RGB 1998 or ProPhoto RGB, instead of CMYK. Side note: All screens use additive color.

What is a Color System?

A color system is a set of colors that represent a specific visual spectrum.* These few colors are mixed together to create a limited usable range, and that range is called a color system. Examples of a color system include RGB, CMYK, and Lab.

* “Appendix A.” Understanding Digital Photography, by Joseph A. Ippolito, Thomson/Delmar Learning, 2003, p. 372.

What is a Channel?

Photoshop organizes your chosen set of colors (e.g. RGB or CMYK) into channels, dividing up your image information by color. For RGB and CMYK, Photoshop also includes a composite channel. Each channel is in grayscale and uses a mask to store each color’s information. You can edit this mask to alter the look of your image and how the channels are mixed.

In RGB and CMYK, you can use the Channel Mixer to change the amount of color information on each channel.

What is a Spot Color?

An additional color that is not a part of an established color system or mode.

For More Information

Linkedin Learning: Understanding CMYK vs. RGB
Linkedin Learning: Understanding Spot Colors
Linkedin Learning: Spot Colors

Registration & Trapping

The Risograph has limits of accuracy. Each color layer requires a separate pass through the printer, registration on multi-color Risograph prints will never be perfect. 

It is recommended that you add registration marks to your image to aid in lining up multiple layers. These can also double as trim marks if you plan on cutting down your print to size. 

Line work printed over solid blocks of color will usually look best.

Registration (aligning overlapping colors) can be tricky and often imperfect on the Risograph.

When colors are misaligned (misregistration), you can be left with a glaring white gap that can detract from your overall piece.

Trapping is a remedy to misregistration. Trapping is the practice of adding a little bit of overlap between adjacent colors to make sure that there are no white gaps between them even when registration is a little uneven. In other words, trapping expands pixels where color channels touch or overlap.

Trapping channels in Photoshop

Select all channels you want to trap.

Trap
Menu bar > Image > Trap…

Select the number of pixels or millimeters you want to trap. (We recommend you do the highest allowable.)

There will only be a slight visual difference in your file, but this will help your colors overlap once you print.

Click OK.

Risograph Image Options

The Risograph can print at 600 d.p.i. and has two gradient techniques to choose from:

  • Grain Touch: a randomized diffusion dither pattern (like a photo or film grain) 
  • Screen-Covered: creates classic halftone patterns on a very small scale.  
    • Screen Frequency controls the size of dots produced (higher numbers = smaller dots).
    • Screen Angle controls the angle that the pattern is set to.

We recommend using Grain Touch over Screen-covered. If you have questions about screen-covered and Riso halftones, please contact the IC.