Leading expert on image preservation, Henry Wilhelm, talks about issues critical to today’s digital photographers.

Throughout the history of photography, the print has always been the main way in which people interact with photographs. Prints are universally accessible; they require no special viewing equipment, so everybody can enjoy them, regardless of their imaging expertise. Prints are also the most common way in which photographs are displayed.

Unfortunately, between the widespread adoption of colour printing in the 1950s and the arrival of digital photo printers in the early years of this century, most photographers handed control over the production of their colour prints to photo labs. Even black-and-white printing was seen as ‘too complicated’ by most photographers until recently, although darkroom techniques have been widely taught in schools and colleges.

In some cases the shift away from photographer-based printing and processing happened because colour materials were too costly and very short-lived. Making prints with natural-looking colours was also beyond the capabilities of many photographers. Even professional photographers either didn’t have the time to run a colour darkroom – or simply couldn’t be bothered. Either way, control of printing passed out of photographers’ hands.

According to Henry Wilhelm, the advent of digital photography has changed that situation radically. ‘One of the most wonderful things of the digital age is that printing has come back to photography,’ he says. ‘We have complete control. It’s like a golden age of photography.

‘Compared to the options we had before – the colour darkroom, making test prints – regardless of the cost of the inks, what we have today is astonishing. You can print your digital photographs in your home, in your apartment and, given that larger prints always cost more, it’s an amazingly economical cost per print. It allows us to do something with beautiful quality, incredible permanence.

‘I get upset at photographers who complain [about ink costs]. Compared to what we had before – and not so very long ago – this is an incredible bargain.

‘At the enthusiast or professional level, all printers are capable of making extremely good prints,’ Wilhelm adds. ‘And they’re so much more accessible than silver halide technology. The only thing you can do to wreck the system is to use third-party inks.’


Results from Wilhelm Imaging Research’s tests comparing Epson’s DURABrite pigment inks and paper (top row) with Calidad inks and papers (bottom row), showing the effects of light exposure on colour stability. (Illustration supplied by Wilhelm Imaging Research.)

Media Testing
Wilhelm Imaging Research (http://wilhelm-research.com/) is the world’s leading independent tester of imaging media and regularly publishes details of lightfastness tests on different papers using both printer manufacturers’ and third party ink sets. Asked how long it takes to obtain lightfastness ratings for new printers when they are released, Wilhelm says testing times can vary, depending on the stability of the inks themselves and whether manufacturers change their ink formulations – albeit even slightly – after a new printer is released.

‘Generally speaking, test times are partly based on the history of the ink sets,’ he explains. ‘In most cases, the time period between measurements is based on expected permanence.’

Under test conditions, which involve exposure to light at the equivalent of 450 lux for 12 hours per day at a temperature of 24 °C and 60% relative humidity, a two month period is equal to approximately 25 years. Media under test are checked regularly to determine the point at which there is noticeable fading.

Data from previous tests is used to predict the fading rates of new inks and papers. Consequently, expected fading times are longer for pigment inks than dye-based inks, although some recently-released dye inks are proving almost as fade-resistant as pigments, especially on porous papers.

‘We try to be very cautious when ink formulation changes occur, as they have with some of Canon’s ChromaLife inks,’ Wilhelm explains. ‘Our focus is what’s on the market and that’s difficult when formulations are being improved.’

Tests on third-party media are often completed relatively quickly. As Wilhelm points out: ‘When we tested the Calidad inks, we expected them to be fairly stable because of the “pigment” claim. But when we took them out for the first measurement we found they had faded far beyond the end point so we had to test them all over again.’

Wilhelm Imaging Research also evaluates resistance to chemical changes caused by exposure to atmospheric contaminants – notably ozone (which is a strong oxidising agent). Pigment inks are highly resistant to ozone. They are also much less reactive with the receptive layer on the paper, which makes printing on matte ‘fine art’ papers practical. In contrast, Wilhelm says, dye-based inks are seriously destabilised on those papers; even the new Claria, Lucia and Vivera inks.

Waterfastness and resistance to high humidity are other areas in which pigment inks are superior. They also out-perform dye inks when it comes to short-term dry-down, producing stable colours from the time the prints emerge from the printer. This makes it easier for photographers to check colour accuracy immediately.

‘To me it’s kind of interesting because we always think of long-term permanence,’ Wilhelm explains, ‘but they [pigment inks] really excel in what happens in the first minutes, hours or days of a print being made. For any kind of proofing application – or if you’re using a colour-managed workflow – this is essential.

‘We consider the short-term dry-down effect a sub-set of permanence. The whole measure we do of permanence is a function of time. Short-term dry-down actually is a function of time, where the neutral scale [for colour shifts] may not be neutral. Wedding and portrait photographers often get reprint orders six months later and to match the original it requires everything to be stable.’

Fine Art Printing
A combination of digital SLR cameras, editing software like Photoshop and capable inkjet printers have made fine art printing possible and accessible for an increasing number of photographers. New ink sets and papers have provided a wealth of opportunities for such photographers, among them the ability to produce excellent B&W prints.

Asked what he – as a photographer – looks for in a printer, Henry Wilhelm’s answer is immediate and emphatic: ‘Permanence. This idea that images can be preserved as digital files is totally flawed. But if you look 25 years into the future, will these things even exist?

‘If you think about pictures you have of yourself as a child – or your parents or grandparents – how many of those could you actually produce a negative for? The print has always been historically the survivor. It requires no special equipment – software or hardware – to retrieve it.’

According the Henry Wilhelm, all professional level printers are now pigment ink printers and, he says, there are many reasons for choosing a pigment printer for fine-art printing. Another factor is their superior performance for black and white printing.

‘I think one of the significant developments in the whole field really solidified itself last year when both HP and Canon introduced multi-level grey pigment inks,’ he explains. (Epson also has three blacks in it’s Ultrachrome K3 inbkset)

‘Remember how hard it was to get a nice, neutral B&W print with just CMYK inks? You can’t do it. With custom profiling you could come pretty close but that’s going to a different audience. You really need three levels of black.’

Amateur Printing
As well as testing fine-art media, Wilhelm Imaging Research also runs regular tests of the printers, inks and papers used for snapshot printing, including both inkjet and dye-sublimation printers and in-store kiosks. The results are sometimes astonishing.

“One thing that is interesting to us in this category is that, in terms of light stability, there’s a 400 times difference between very best products and the worst,” Wilhelm explains.

Most dramatic are the differences between prints made with printer manufacturers’ media and those made with ‘third-party’ products, some of which are extensively promoted and widely available in department stores and supermarkets all round Australia. Many are marketed with claims Wilhelm’s testing has proved to be fallacious.

‘Given all the progress the industry has made in printing technologies, one of the things that really bother me …is to see the performance of third-party inks. It’s like going back to the Stone Age,’ Wilhelm says. ‘For some of the worst products in terms of permanence on display you would have to go back before World War II to find equivalents in silver halide media.

‘What really has upset me about this is that the marketing pitched to the consumer [by third-party media producers] claims the quality of the inks and photo papers is equal to or better than the original manufacturer’s media at a lower cost. Completely left out of that definition of “quality” is permanence. The reason we take pictures in the first place is to preserve something.

‘In the course of the studies we’ve been doing I was flabbergasted at how bad the initial image quality [of some third-party products] was. Like, grey scales are nowhere near neutral, right out of the box! I think some consumers don’t realise how bad that can be.

‘In contrast, I look at little inkjet printers, like the PictureMate, which can print without a computer and have a wider colour gamut, better sharpness and much better image permanence than anything that ever existed before. Never before in the history of photography has it been so easy to make good colour prints.’

Permanence is always a value-added thing, Wilhelm concludes. ‘If you show anyone two prints that are otherwise more or less equal but one is half as permanent as the other, they’ll always choose the more permanent print – even if they may not have thought about permanence before.’

About Henry Wilhelm
Henry Wilhelm has been investigating image conservation since 1970 and is widely regarded for the rigour and technical competence of his testing programs, which are supported by all leading printer and media manufacturers. As co-founder (with partner, Carol Brower Wilhelm), president, and director of research at Wilhelm Imaging Research, Inc., he appears frequently as a speaker on inkjet printing technologies and print permanence at industry conferences, trade shows, and museum conservation meetings. Since 1995 he has been an advisor to Corbis on the long-term preservation of the Corbis Bettmann photography collections, which contain more than 65 million images.

A keen photographer, he owns a Canon EOS 5D camera and uses Epson’s Stylus Pro 3800 to print his digital photos.