Thinking about Inks

The printing heads in inkjet printers are precision-engineered to perform a specific function: placing thousands of tiny ink droplets accurately on a sheet of paper to create a photo print. Ink is a critical component in the system. Each printer manufacturer formulates inks to meet the needs of the print heads in printers in their range. In some cases there is a different set of inks for each individual printer; in others, one ink set can be used with several models in the range.
Why it’s Vital to Use the Correct Ink
As we explained in Choosing the Right Printer, different types of inkjet printer require radically different ink types. Printers designed for dye-based inks can’t work with pigment inks – and vice versa. Thermal inkjet printers need inks that can maintain a specific viscosity range through repeated cycles of heating and cooling, while piezo-electric printers require inks with highly specific viscosities.

Inks that do not meet the print head’s requirements can either leak through the nozzles or clog the print head. To prevent potential problems, buying the manufacturer’s inks ensures you will be using an ink that exactly meets the requirements of your printer.

Although there may be cheaper inks on sale in supermarkets and department stores, using them for photo printing is risky for the following reasons:

1. There is no way to guarantee the performance of third-party inks and no evidence they were produced with adequate quality control or whether they are suitable for a specific printer.

2. Cheap ink cartridges are often poorly-manufactured and may be susceptible to leakage, allowing inks to spread inside the printer’s electronics and mechanical components. This can damage cables, circuit boards and associated mechanical parts.

3. Many cheap inks are also too acidic and can etch the nozzles in the print head.

4. If you combine different ink types and formulations by buying from different manufacturers, the chemicals in the inks may react and coagulate. This will clog and damage print heads and may cause internal damage to the printer.

Consequently, if you want to make the best-looking, longest-lasting and most colour accurate prints, the only way to achieve these objectives is to print with the inks made by your printer manufacturer. It’s the only way to be assured that the inks will be manufactured to high quality standards and subjected to rigorous quality control.

Equally importantly, it’s the only way to guarantee repeatable colour accuracy from print-to-print, regardless of how long it was since the original print was produced. Finally, manufacturers’ inks are your best guarantee that your prints will remain bright and colour accurate over time.

Pigment or Dye Ink?
The earliest inkjet printers used dye-based inks made from coloured liquid dyes dissolved in a carrier fluid. Dye-based printers still comprise the majority of the cheaper models on the market, although there have been huge improvements in their performance since the early days of inkjet printing. Some A3+ printers have been designed specifically for dye-based inks to capitalise on certain performance characteristics.

Epson’s Stylus Photo R1410 A3+ inkjet printer has been designed to take advantage of the fine detail and brilliant colours produced by dye inks.

Although black pigment inks have been used for document printing for many years, until recently, no coloured pigment inks were produced. Several years ago, Epson pioneered the use of complete pigment ink sets with both black and coloured inks, first in its professional printers and then in printers designed for photo enthusiasts. Other printer manufacturers have followed suit. Today, photographers can choose between the two technologies, depending on the results they wish to obtain.

Dye inks are cheaper to manufacture and, being liquid, can be forced through finer nozzles than pigment inks. Consequently, dye-based printers should be able to reproduce slightly finer detail than pigment-based printers. Because ink formulators have a wide range of colours to choose from, better quality dye ink sets can cover a slightly wider colour gamut than pigment inks.

Pigment inks contain millions of tiny solid particles of coloured pigment suspended in a liquid carrier medium. In the early days of the technology, ink formulators had a limited range of colours to choose from. However, recent developments and the use of specialised processes like resin encapsulation have almost eliminated the differences in colour gamut between the two ink types.

The latest pigment inkjets use resin-encapsulated pigment particles, which are more robust and provide a wider colour gamut that earlier pigment inks.

Dye and pigment inks behave differently when placed on printing paper and each type has its own vulnerabilities. Dye inks soak into the surface of the paper and may spread, causing a loss of precision in edges. But prints made with dye inks are usually scratch-resistant. Pigment inks remain on the surface of the paper, where they are vulnerable to physical abrasion and scuffing.

In the past, dye inks were much more liable to fade than pigment inks. However, some recent dye ink sets come close to matching the longevity and lightfastness of pigment inks. Early pigment inks sets were vulnerable to a phenomenon known as ‘metamerism’ which caused them to look slightly different in colour under different types of lighting. This problem has been largely solved in the latest pigment inks.

So, which type of ink should you use? The table below compares their key features.

For prints that will be framed behind glass, it doesn’t really matter which type of ink/paper combination you choose because the glass will largely eliminate the differences between the two ink types. However, prints made with pigment inks will have greater lightfastness as a rule.

How Many Inks?
The more inks a printer uses the greater the range of colours and tones it can reproduce. The simplest printers use only four ink colours: cyan, magenta, yellow and black. Printers with this ink set are known as ‘CMYK printers’, with the K standing for ‘key’ and representing black.

A typical four-colour ink set.

In theory, all colours should be reproducible by combining varying proportions of cyan, magenta and yellow. However, in practice, it is impossible to produce inks with totally pure colours and full saturation so the black ink has been added to add depth to the other hues.

Four-colour ink sets are limited in the subtlety of the tones they can reproduce. To improve tonal reproduction and provide greater colour accuracy, manufacturers introduced two additional inks: light cyan and light magenta. These six-colour inkjet printers were the first step towards photo-quality inkjet printing and the first inkjet printers to match the quality of traditional photo prints.

A typical six-colour ink set with light cyan and light magenta added to the basic CMYK set.

Subsequent additions of coloured inkjet have mainly involved fine-tuning of the printers’ colour palettes. The typical eight-colour ink set contains cyan, magenta, and yellow inks plus black and two levels of grey ink. In some printers separate black inks are required for printing on glossy and matte papers. You often have to take out the Photo Black cartridge and replace it with the Matte Black cartridge before you can swap from glossy and semi-gloss media to matte papers.

A typical eight-cartridge ink set with yellow, magenta, cyan, light magenta, light cyan and three levels of black ink (black, light black and light light black). Two types of black ink are included: Photo Black and Matte Black.

Red, blue and green inks have been added to some dye ink sets to increase the brilliance of these colours in prints of landscape and product shots. Orange has been added to improve the accuracy of skin tones and Epson has recently introduced a new ink set with more vivid magenta and light magenta inks to further improve overall colour accuracy.

One of the newer ink sets that includes separate Photo and Matte black inks plus red and orange in addition to the basic CMY colours. The additional Gloss Optimiser (GO) cartridge overlays a resin coating on prints on glossy media to provide a smoother surface.

The number of actual colours used in eight-cartridge ‘system’ printers varies. The eighth cartridge in Epson’s Stylus Photo R800, R1800 and R1900 pigment-ink printers is a Gloss Optimiser cartridge containing the resin that is used to coat the pigment particles in these printers’ inks. Designed to produce a high-gloss finish on glossy papers, it ‘fills-in’ the surface irregularities produced by printing with pigment inks on glossy papers. The resin coating on the surface of the print provides a smooth, reflective surface and adds a protective layer to the print.

Recently, Canon and Epson have added 10-colour printers to the professional end of their ranges. In each case, the additional cartridges are used for different types of black or grey inks, which are added to the standard eight-colour ink set. Black-and-white printing has been radically improved by the addition of mid-grey and light-grey inks, which rectify the deficiencies of the standard ink sets and remove residual colour casts. Photographers who enjoy printing monochrome pictures should always choose a printer with three black inks. (More information on B&W printing can be found in Monochrome Printing.)

Ink Costs
Consumers often complain about the high cost of inkjet cartridges. It’s a complex issue that is often poorly understood by the average person-on-the-street. Essentially, the major element in the cost of an inkjet cartridge is the ink delivery mechanism, which must be engineered and manufactured to a high degree of precision. The actual cost of the ink is comparatively low so it makes little sense to compare it with, for example, perfume costs.

So why don’t manufacturers make larger ink cartridges?

One reason relates to the physical size of the printer. To support larger ink cartridges the print head must be larger and more robust. This adds size, weight – and additional production cost – to the printer and these costs must be passed on to purchasers.

Essentially, there’s a limit to how much the manufacturers can charge for ink cartridges and, since ink is relatively inexpensive, they must be seen to provide reasonable value for money. The cartridge market is very price-driven and because manufacturers have a fixed cost for producing the cartridge itself, the only flexibility they have is in the amount of ink they put in it.

In the near future you should be able to buy standard and high-capacity cartridges for a much wider range of printers – and even extra-high capacity cartridges for a few models. The size of the print head and sturdiness of the printer’s construction will doubtless dictate which models will support the new cartridges.

The best way to evaluate ink costs is to compare how much it costs to produce prints in a range of sizes from snapshots up to poster size. Going on the printing costs we’ve assessed by reviewing a wide variety of printers, it is difficult for home-based printing to match the cost of the cheapest kiosk-based services at snapshot print size. However, once you move to A4 size and larger, it becomes much cheaper to print at home – regardless of the cost of the printer and media you use.

Getting the Most From Your Ink Cartridges
By design, most printers will indicate when ink levels begin running low – often when there is 20% or more of the ink remaining. So it’s wise to continue to print until the printer indicates the cartridge can no longer be used. Note: the cartridge will always have some ink remaining at this point. This feature prevents the nozzles in the print head from running dry, which will reduce print quality and create printer maintenance problems.

A typical reminder screen showing a low ink level for one cartridge.

The amount of remaining ink will vary for many reasons (the number of cleaning cycles the printer has been through, the types of prints made, the number of times the printer has been switched on or off, and how long it is left on and not operating). By controlling these factors you can maximise ink yields. The following tips will help you to minimise ink wastage:

1. Don’t run cleaning cycles unless your prints are showing signs of a blocked nozzle (missing dots or lines). Ink is used each time a cleaning cycle is run so the fewer times you have to clean the nozzles, the less ink you waste.

2. Think carefully about print resolution and set the appropriate resolution for the output size and application. Documents can usually be printed at lower resolution than photographs. Photo prints at A4-size and smaller should be printed at 300 dpi (dots/inch) resolution, while larger prints can be printed at lower resolutions (250 dpi or 200 dpi for A3 size or 150 dpi for larger sizes). Large prints are viewed from greater distances so the amount of detail required is less.

3. Experiment with your printer’s output quality settings to find the most economical one for each application. Don’t assume the highest quality setting is the only one to use for photo prints. You may find there is very little difference in photo prints made with the top quality setting and the next one down, yet the amount of ink used with the top setting is substantially higher.

Some printers provide several quality settings, usually with differing resolution. The difference between the highest and one step down may be difficult to detect with some images.

4. Don’t leave your printer on when you’re not using it. Most printers will automatically run periodic head cleans to ensure the nozzles aren’t blocked by drying ink while they are switched on.

5. Always turn off the printer from the front control panel, before you switch off the wall switch. This positions the print head in a protected position that reduces the chance of the nozzles drying out.

Covering All Colours
To get the best performance from an inkjet printer the inks must be able to reproduce a full range of colours. This is known as the ink set (or printer’s) colour gamut. Colour gamuts vary with different ink types and different combinations of inks. The latest inks can reproduce most – if not all – of the colours and tones you can see on a computer screen and it doesn’t matter whether you print with dye or pigment inks, you should still be able to produce good results.

But some printers and ink sets do deliver superiors results – and you can tell by their wider, smoother gamut plots. The illustrations below compare the colour gamuts from two printers.

The gamut plot above shows many uneven areas, which represent where colours will not be reproduced to their full potential.

The smooth gamut plot indicates the printer and ink set are capable of accurate colour reproduction.

The latest ink sets also provide wider gamut coverage. Compare the colours in the images below to see the subtle difference different ink sets produce.

An image printed with Epson’s K3 pigment ink set.

The same image printed with Epson’s new K3 with Vivid Magenta inks. Note the subtle improvements to skin tones and richer blues.

Recycling Spent Cartridges
What should you do with a used inkjet cartridge? If you throw them in the rubbish bin they end up in landfill, which is not good environmental practice. It’s much better – and very easy – to recycle them. The leading printer manufacturers have joined forces with Planet Ark, which co-ordinates a recycling service,
. Participating manufacturers support the recycling service by covering the cost of collecting and recycling the cartridges.

The Cartridges 4 Planet Ark program is a nationwide recycling program supported by all leading printer manufacturers. Collection boxes for spent cartridges can be found in most post offices and selected retail outlets.

There is no cost to members of the public who wish to recycle cartridges. Collection boxes have been set up in a number of retail outlets around Australia, including Australia Post, Officeworks, Harvey Norman, Tandy and Dick Smith Electronics or PowerHouse outlets. You simply take your used cartridges to one of these outlets and drop them off.

All the printer cartridges collected are sent to Close the Loop for sorting and processing. All inkjet cartridges, toner bottles and drum units are processed to recycle their component materials into new products. The ultimate aim is to return the raw materials back to the original equipment manufacturer for re-use in new cartridges. Cartridges that cannot be re-manufactured are recycled.

The recycling process is very efficient and covers everything from the plastics, aluminium, steel and toner powder. Even the ink from inkjet cartridges is used in lower grade printing applications. The collection program is also available free of charge to selected businesses and government departments anywhere in Australia simply by calling 1800 24 24 73.

USEFUL URLs
The following websites provide additional information on the topics covered in this chapter.

www.planetark.com.au for information on ink cartridge recycling.
www.epson.com.au/videos/ for information on inkjet inks, cartridge design and an interview with Henry Wilhelm on the importance of ink and media in achieving print permanence.

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