Editor › Learn › Rich Black vs Plain Black vs Registration Black
What is the difference between rich black, plain black and registration black?
Plain black is 100% K alone — correct for text and thin lines because it needs no registration. Rich black adds supporting ink under the K (a common coated-stock build is around C60 M40 Y40 K100, but ask your printer) so large solid areas print dense instead of thin dark grey. Registration black is 100% of ALL plates — a technical swatch that exists so crop and registration marks appear on every separation; using it for artwork violates ink limits and is never correct.
Why plain K for text
A press prints each plate in a separate pass or unit, and mechanical registration between plates is good but not perfect. Small type built from four plates shows any misregistration as coloured halos on every glyph edge. Type built from the K plate alone cannot misregister against itself — which is why body text in professional print is 100% K, and why profile-driven conversions keep neutral text on the K plate.
The same logic gives the standard companion rule: black text over images or tints should OVERPRINT rather than knock out, so a hairline registration error does not open white gaps around glyphs. Overprint settings live in layout applications; from the raster side, your job is delivering text as clean single-plate black.
Why rich black for areas
Solid 100% K over a large area prints as a slightly translucent dark — hold a K-only panel next to a photo's deep shadow and the panel looks weak. Adding under-colour beneath the black raises density and gives the black a controlled character: cooler with more cyan, warmer with more magenta. The build is condition-specific — heavier stock and coated paper tolerate more; your printer's recommendation beats any internet recipe, including the one in this article's answer.
The three blacks, side by side
| Build | Use for | Never for | |
|---|---|---|---|
| Plain black | K 100 only | text, thin rules, barcodes | large solid panels (looks thin) |
| Rich black | CMY support + K100, per printer | large solids, backgrounds | small type (registration halos) |
| Registration | 100% every plate | printer's marks only | ANY artwork — violates ink limits |
How raster conversions handle this for you
In photographic content you rarely construct blacks by hand: the profile's black generation decides how much K replaces CMY in dark neutrals, inside the ink limit. The rules above matter most where design meets raster — flattening a layout into an image, building a background panel, or checking that imported text stayed on the K plate. The plate-isolation habit from the ink-coverage article is the fastest check.
Try it in PhotoAIA
- Create a CMYK document and fill one rectangle with pure K black and another with a rich build.
- View the composite: the rich panel reads denser.
- Isolate each plate in the Channels panel: the plain panel exists only on K; the rich panel shows its support inks.
- Add small white text on each and imagine a 0.1 mm plate shift — the four-plate panel is where halos would appear.
Questions
- Why does my black background look different from my black text in print?
- Almost certainly one is rich black and the other plain K. Decide which black the design needs and make it consistent — and expect large areas to WANT the rich build.
- Is there one correct rich black recipe?
- No. Builds around C60 M40 Y40 K100 are common starting points for coated offset, but the right build depends on stock, press and the black's intended character. Ask the printer; it is a routine question.
- What happens if I use registration black in artwork?
- Up to 400% ink in that area: drying problems, set-off, and a guaranteed preflight failure at any competent printer.