Epson WorkForce Enterprise WF-C21000 ink cartridge, yellow

Of the three base colours yellow is the lightest, yet without it a printer can produce neither green nor orange. With cyan it forms greens; with magenta, reds and oranges. Sunlight in photos, yellow highlights in spreadsheets, green charts and warm skin tones all need yellow ink, even when a page contains hardly any pure yellow.

On white paper, missing yellow text is hard to notice, because yellow is rarely printed on its own. The change appears in mixed colours instead: greens turn bluish, oranges turn reddish and photos look cold. That is why the yellow cartridge deserves the same attention as the others, especially before a large colour print run.

The supplier marks one printer as compatible, the WorkForce Enterprise WF-C21000 D4TW, and no other devices appear on the list. The cartridge carries the product name WF-C21000, which helps tell it apart from the AM-C400 and AM-C4000 cartridges of the same series. Check your printer's model label before installing it to make sure the names match.

Epson is listed as the manufacturer, so this is an original consumable. The pack is single and holds yellow ink only: when it runs out, the cyan and magenta cartridges keep working in the printer. Each colour is used up at its own pace, and you replace only the cartridge that is genuinely empty.

It suits companies and print rooms that run a WorkForce Enterprise WF-C21000 D4TW and prefer the manufacturer's original consumables. A spare is especially useful if you often print green charts, maps or photo-heavy material. The supplier gives no page yield, so judge consumption by the ink level the printer reports.