Inkjet Printing


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With better equipment and inks coming on the market all the time, inkjet printing is becoming easier; but often results are not as good as they might be. Here we go into more detail about making better prints. 


Some common questions are: 

inkjet print

Why don't my prints look like the screen image?
How long will my prints last?
Are third-party inks any good?
What do suppliers mean by archival?
What is metamerism?
How can I fix printing problems?
Can inkjet prints be better than photographic prints? 



The Monitor

monitor

Before inkjet printers can produce their best, colour management needs to be understood and put into practice. The Colour Managementtutorials on this site give a explanation of this subject.

We must start with a properly calibrated monitor. The only way to achieve this satisfactorily is with the right calibrating hardware and software. 
The ideal is to buy the necessary equipment then calibration can be checked on a regular basis, because monitors do deteriorate and change colour over time.

Some companies offer an on-site calibration service, but this can be expensive and normally only professional photographers, design studios and printing houses go this route.
For non-professionals who feel they cannot justify the expense of buying their own calibrator, some makes like the Gretag MacBeth Eye One have an open licensing system, which means the device can be used on many different computers. The calibrator can then be bought by a group or photography club and shared. Firms like ColourTools and Chromix sell these items.
Suitable equipment for monitor calibration is not too expensive these days
.

Some people offer a modestly-priced calibrating and profiling service and travel around camera clubs giving talks and offering their service.

It's a waste of time and money getting a profile for your printer unless the monitor it set up properly first. Whether one is using Photoshop or any other digital imaging software, if the monitor is not accurate, the prints can never be.
The tutorials mentioned above go into more detail here.

When the monitor is set up accurately, then we can turn our attention to the printer.

A perfectly performing printer has many advantages:

  • A print that comes out looking like the image on the screen every time.
  • No messing about with colour settings trying to get the print correct in all areas.
  • Blues coming out blue and not purple.
  • Less wasted ink and paper on all the rejects.
  • Many inkjet printers are programmed to lay down too much ink. This makes blacks look cloggy and pushes up the ink bill.
  • Less frustration and less swearing at the equipment.



The Printer

So now you've got an accurate monitor and you find the prints don't look like the image on the screen. 
There are several reasons for this.


  1. The monitor works in red, green and blue, the primary colours, which make up white light when mixed together. Unfortunately, it is not possible to print successfully with red, green and blue inks. This is nothing to do with photography or computers nor is it is the fault of Epson or Hewlett Packard; it's always been the case.
  2. Offset and inkjet printers alike use cyan, magenta and yellow with a separate black to help the mixture along. A monitor will display thousands and often millions of colours. CMYK inks cannot produce anything like this number. A green on the screen will be produced with a mixture of cyan and yellow and it might look fine. A blue will be produced from cyan and magenta and it probably won't look much good.
  3. A monitor, like a transparency, is lit from behind and has a vibrancy. Printing on to paper and the use of reflected light takes away much of this vibrancy. The characteristics and tone of the paper also affect the final colour.
  4. Inkjet printers vary in their results because there are slight variants in the machines themselves.
  5. Of even greater importance are the papers and inks used; they will all produce different results. 
    We know the monitor uses an RGB colour space while a printer uses a smaller CMYK colour space. This means the large range of colour on the RGB display has to be squeezed into the CMYK colour space, which can only reproduce a much smaller range or gamut of colours. To bridge the gap between the monitor and a specific printer with its own specific inks and paper, very accurate settings need to be put into the system. This is the job of the printer profile.



A profile for digital inkjet printing is made for a particular printer, one type of paper and one set of inks. 
That specific profile will not work accurately on all inkjet printers, even of the same make. It is a custom profile for one set of circumstances. Once you've decided on a certain fine art paper and suitable inks, the profile will work well on that combination. Change the inks or the paper and the results won't be the same; you'll need a new profile. 


Test print

There are numerous suppliers of this profiling service and they will supply the image file made up of many small colour patches. 
This file is printed out and the patches are then measured by a spectrophotometer, which reads the LAB colour values on the print. 
These values are compared with the RGB values of the master print. The colours are compared via the LAB colour space and the results are entered into the colour settings to bring the colours produced by your printer in line with the master print.

Finally your prints will look like your monitor display. Making the printer profile itself is more complicated and requires expensive equipment. For someone who is going to use more than one printer and a variety of papers and inks, it can be worth making their own profiles. 
Spectrophotometers can be purchased, but they aren't cheap and the more you spend, the better. However, they still require a lot of experience to get the best out of them. Most people will be better off using a specialist service. Some firms offering this service can be found at the end of the Colour Management tutorials. 



Inks and Paper

The rest of this page and the following page are not meant to be a definitive survey of inks and papers. 
They provide an overall picture of inks, papers and inkjet printing. Greater detail on the topics discussed can be found in the links found throughout the text.

There are two types of inks: dye and pigment
Dye based inks have molecules of dye dissolved in water. 
Pigment inks contain small particles of coloured pigment suspended in water. Both inks are water based.

For run-of-the-mill printing, just about anything will do. Standard inks and paper which come with any printer or some of the independent althernatives will give decent or even extremely good results. 
The big snag is they will not last. Exposed in a reasonable amount of light, they are likely to fade in a few weeks. 
For long-term survival, special attention needs to be paid to inks, paper and display conditions.

Giclée or Archival
Photographers producing fine art prints are concerned that they will last a considerable time. 
Traditional photographic processes can make prints which last for years, decades or forever. Inkjet prints have some catching up to do. 
In America, photographers making fine art prints wanted to distinguish their prints from standard inkjet printing, which is produced on any basic printer.

To identify them, the term Giclée was coined. 
Personally I cannot bear to use the word. In French, it comes from the word meaning 'to spout'. That's all right, but in French slang, apparently it means 'to ejaculate'. Enough said.

I prefer the terms Archival Prints or Fine Art Prints. It is becoming generally understood that fine art prints are archival, although the degree of archival-ness can vary. 



Fading Tests

archival print

Inks are tested for their stability by manufacturers and to some extent by independent organizations. Tests can be misleading, however, because there is not yet a universal standard for fade tests and the criteria used by different suppliers can vary. 
How long a particular ink will last also depends on the paper it is printed on.

The format of testing used by some involves:

  • the equivalent of 450 lux of filtered fluorescent light
    for 12 hours a day;
  • no direct sunlight;
  • prints must be under glass;
  • humidity level is at 50%;
  • a temperature of 24 degrees C.

There is a move to make this specification an ANSI/ISO standard.

Fading tests are simulated tests, which means prints are exposed to extremely high levels of illumination and the stability times of the prints is extrapolated to find 'realistic' hanging times.

Just to be practical, accelerated test have to be used; a 100 year wait is a little inconvenient. The relationship between an ink's durability in an extremely high level of illumination and an ink's durability in normal conditions is not necessarily consistent between different inks.

It seems that pigment inks last better than dye inks under very high light levels but under normal display conditions the difference may not be so great. 
All products for inkjet printers are fairly new, so caution needs to be exercised when dealing with longevity. Silver halide prints and other photographic processes have been around a long time and their position is much more clear-cut.


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