The Difference Between RGB and CMYK
Your screen and our press make color in two completely different ways. Pick the wrong mode and the printed job comes back looking flat or off. Here is what each one is for, plus the ink limit to watch when you are mixing dark colors.
RGB
For screens only. Phones, laptops, TVs, projectors.
RGB makes color out of light. Red, green and blue light mix together and get brighter the more you add, which is why a screen can show neon greens and electric blues that no ink can reproduce on paper. Use RGB for anything that stays digital: your website, social posts, email banners, presentation slides.
Send us an RGB file and it gets converted to CMYK before it goes on press. That conversion is automatic, but it has limits. Colors outside the CMYK range come back duller than they looked on your monitor. If the color matters to you, work in CMYK from the start.
CMYK
Made for printing on paper.
CMYK makes color out of ink. Four of them: Cyan, Magenta, Yellow and Key (Black), laid down as separate layers. Ink absorbs light instead of emitting it, so the more you add, the darker the sheet gets. Every press works this way, ours included. Design in CMYK for anything physical: name cards, flyers, booklets, stickers, packaging, banners.
Set your document to CMYK before you start, not after. Illustrator: File > Document Color Mode > CMYK Color. Photoshop: Image > Mode > CMYK Color. In InDesign, set the document Intent to Print and build your swatches as CMYK. Most color surprises come from converting a finished RGB design at the very end.
Watch Your Total Ink Coverage
Keep your four ink values adding up to 240% or less.
Each ink runs from 0% to 100%, so on paper a single color could total 400%. In practice that does not work. The inks physically stack on the sheet, and past a point the paper cannot absorb any more. The area goes muddy and almost black, the ink stays wet longer, and it can set off onto the back of the sheet stacked on top of it. Any fine detail sitting in that dark area disappears.
Add up C + M + Y + K on any swatch. We work to a maximum of 240% total ink coverage. Anything above that, bring it down before you send the file.
Black is the usual culprit. A “rich black” mixed as C100 M100 Y100 K100 comes to 400%. Use C60 M40 Y40 K100 instead. That lands exactly on 240% and still prints as a deep, solid black. For body text and small type, stay on K100 on its own. Four-color black text goes soft the moment the plates shift even slightly.
To check as you go: in InDesign use Window > Output > Separations Preview, switch View to Ink Limit and set it to 240%. Anything over the limit shows up in red. In Photoshop, open the Info panel, set one readout to Total Ink, then hover over your dark areas. On a finished PDF, Acrobat Pro does the same under Print Production > Output Preview > Total Area Coverage. Illustrator has no ink-limit preview, so read the CMYK values off your swatches directly.
Not Sure? Check With Your Designer
If you are not certain your file is set up correctly, ask your design studio before it comes to us. They have the working file. Fixing the color mode or bringing the ink coverage down takes them a few minutes at that stage. After the job has printed, the only fix is a reprint.
We print the file you supply, as you supply it. Worth a quick check with your designer first.