Epson's UltraChrome K3 inks include eight cartridges—two shades of cyan, two shades of magenta, yellow, and three shades of black.
Some of Canon's printers use 12 separate ink cartridges. Courtesy of dc.watch.impress.
A One way to think of
a gamut is as a set of colored pencils. A set with a few pencils (top) has a small gamut while a set with many pencils (bottom) has a large gamut. Courtesy of Prismacolor at www. prismacolor.com
Your choice of ink, like your choice of paper, determines how bright and colorful your prints are and how long they will last. Usually you make your choice about inks when you buy a printer because printer manufactures try to lock you into using only their inks. They have gone so far as to embed chips in their cartridges so they can't be copied legally. But this isn't always a bad thing. The most reputable paper companies do extensive R&D to ensure that their ink/paper combinations work well together. With cheaper, or off-brand inks, you are likely to get less quality and shorter life spans.
Some newer printers use up to 12 separate colors: the original CMYK plus lighter versions of cyan and magenta, different shades of black, and other colors. Some printers can also vary the size of each dot it prints, giving the printer even more flexibility. Dilute inks and smaller dots improves
the smoothness of tones, especially in areas with low densities such as the highlights in a person's face. Without dilute inks or smaller dots the only way an inkjet printer can create these lighter tones is to leave out droplets. The result is a granularity or lack of smoothness to these areas in the image. Multiple blacks lets you make quality black and white prints. Colors other than cyan, magenta and yellow let the printer form colors with less ink.
Some printers have all of their colors in one multi-segment cartridge and others in separate cartridges. The advantage of the separate cartridges is that you can replace one color without having to replace all of the others at the same time. No matter how they are packaged they come in two basic varieties: dyes and pigments.
- Dye-based inks have colored dyes dissolved in a fluid carrier. When applied to the paper, the dyes are absorbed very evenly so they reflect light very evenly, providing a wide range of bright colors.
- Pigmented inks are small colored particles, often encapsulated in a polymer
or resin coating and suspended in a liquid carrier. The particles are not distributed on the paper's surface as evenly as dyes are, so the light scatters more, and the range of colors tends to be narrower than dye-based inks.
The range of colors a printer can reproduce is called its gamut. Although dyebased inks generally have a wider gamut, they tend to be less stable. For one thing the ink layer on the paper isn't as thick as one created by pigmented inks. For another, dyes are more affected by exposure to sunlight, ultraviolet, and ozone. Pigmented inks are preferred where longevity is desired. However, gaps between the two inks are closing as improvements are made in both areas. Dyes are becoming more stable and pigments are becoming smaller and more uniformly distributed.
When choosing and using inks, here are some things to consider:
- If your prints have horizontal banding or other problems, use the printer's utility program to clean and align the printhead. Printhead nozzles are so small they can be blocked by paper dust, ink residue, or dried ink.
- Most inkjet inks are water based so it's important that you keep water away from the printer or finished prints. Paper and ink companies are working to develop inks with more water-resistance.
- When an ink cartridge runs out, leave it installed in the printer until you are ready to replace it. This helps prevent the ink in the print head nozzles from drying out.