The ABCs of printer inks

Marco Tabini
28 May, 2011
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Buying a printer shouldn’t be difficult, but often, it is. That’s partly because of the vast abundance of technologies, manufacturers and models to choose from.

In order to make an informed decision, you need to consider issues far beyond the basic cost of purchasing and owning the printer and focus on factors like speed, paper capacity and ink technology.

Inks can be particularly esoteric; the terminology surrounding printing inks is often confusing and manufacturers don’t always offer a good overview of the strengths and weaknesses of the choices available.

Fear not, however, for this handy guide will shed light on the most common ink technologies and provide basic information on how they work and which tasks they’re best suited for. Hopefully, this guide will to steer you in the right direction and help you eliminate large classifications of printers from consideration so you can concentrate on the choices most useful to you.

Ribbon inks
It’s only fitting that we start with what is probably the oldest of all the mechanical ink technologies: the trusted ribbon. This remnant of the typewriter era somehow doesn’t want to vanish completely, despite the advent of more modern ink-transfer methods.

Once very popular, ribbons today are limited to specialty applications. For example, old-school fabric ribbons are still used in environments that emphasize reliability at the expense of quality, such as receipt printing.

However, other ribbon types, like thermal transfer ribbons, can produce very high quality output and can often print specialty dyes, like metal foil, that are not easily replicated with other technologies.

Thermal paper
Thermal paper is infused with a chemical substance that turns dark when exposed to heat. It has a number of advantages over traditional printing technologies because there’s no need to keep an ink reservoir filled. That makes the mechanical design and use of the printer both simple and extremely quiet.

For this reason, thermal paper is often used in applications where reliability and ease of maintenance are paramount; at the consumer level, this usually means label printers, like the ones made by Dymo and Brother.

On the downside, thermal paper is expensive and can generally print only in one colour. Another major disadvantage is that its quality decreases quite rapidly in the presence of a hot surface – like, say, the dashboard of a car on a hot, sunny day, to which I personally have lost several rolls of labels.

Liquid inks
If you’re using an inkjet printer, you’re using liquid ink, whose formulation is often not very different from what you would find in, say, the fountain pens of yesteryear. Inside the printer, the ink is forced by a variety of methods through very tiny nozzles in the printing head, thus “painting” dots on paper that eventually form an image or text.

Most consumer inks are water-based dyes, ideal for applications where high-quality output is essential, such as photographs and drawings. Because of their formulation, however, these inks suffer from two major defects: first, they tend to bleed into the paper; and second, they are not colourfast and often fade over time.

The easiest way to solve the first problem is to use the right paper. Special inkjet-specific stocks are manufactured so that they do not easily absorb water, thus forcing the ink to dry on the surface and form crisper images.

For the second problem, you will want to look into archival quality inks, formulated with special pigments that resist fading and rely on a solvent other than water to make them waterproof. In addition, there are paper stocks specifically designed to resist yellowing and degradation for archival purposes. These tend to be sold with higher quality and more expensive photo printers.

Solid inks
Solid ink was originally developed by Tektronix, a company that was eventually acquired by Xerox, which today makes printers based on the technology.

Solid ink is a candlewax-like substance sold in small blocks – one type for each of the primary process colours that form images on paper (cyan, magenta, yellow and black, or CMYK). Inside the printer, the ink is melted and squirted onto an oiled roller using a technology similar to that of offset printers.

The main advantages of solid ink printing are that it is fast, reliable and environmentally friendly – inks are non-toxic and safe to handle. However, the initial investment is usually higher than that of a laser printer.

Although their photo quality is not quite as good as an inkjet, solid inks can be used to print high-resolution colour graphics and generally make exmobileent office machines due to their low maintenance cost. (My office has had one for the last 10 years and we’ve never had to service it beyond replacing the consumables.)

Toner
Toner is the ink of laser printers; typically, it is made by bonding a pigment to a polymer to create a fine powder with particular electrical properties.

Inside the printer, a laser beam ‘paints’ the image to be rendered on a drum, loading it with an electrostatic charge. The drum then rotates over the toner reservoir, picking up particles of ink that are later transferred to paper and melted in place.

Toner is excellent in terms of durability and quality, especially for applications like printing text and line art. Once it’s fused to the paper, it doesn’t fade or come off easily. It doesn’t fare as well for photographs, however, where inkjet printers provide finer resolution and, therefore, better output.

Dye sublimation
The final type of ink technology we’re going to look at is dye sublimation, in which a special dye is rapidly heated so that it goes from a solid to a gaseous state without passing through a liquid phase. The resulting ‘cloud’ of dye is then deposited onto the paper, where it forms a dot of colour.

Unlike inkjet technology, the dots printed by a dye-sub printer have fuzzy edges that blend into one another, resulting in the high-quality output of photographs, particularly when used with specialized paper.

Combined with the high cost of ownership, however, that same feature makes dye sublimation less than ideal for printing content that has very sharp edges, like text or vector art.

A printer for every purpose
One interesting facet of the printer market is that many specialized ink technologies are becoming much more affordable to consumers and general businesses. That makes owning several specialized printers a much less crazy idea than it once was.

Still, not everybody has the budget or patience (not to mention desk space) to deal with multiple printing devices. In that case, the ideal approach is to find the printer that best fits the typical print job that you have to do most often. For the odd job that doesn’t fit your overall technology choice, you can always consult a local specialist or go online.

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