It was whilst working on a storage and movement project at Tate that I first found out about Iris prints – an early inkjet printing technology which became popular in the 1990s for making art reproductions, fine art prints and photographic images (Juergens, 2009). After I was advised by a colleague about their inherent fragility, I decided to research further.

History

The Iris printer was manufactured in the 1980s to produce colour proofs for the printing industry, but artists and photographers were soon drawn to the photorealistic qualities of the prints. Iris printers produced images which were far sharper than other inkjet prints at the time; their dye-based inks had excellent colour gamuts, and they could be produced on a wide variety of high-quality fine art papers. For these reasons, Iris printers became the most widely used technology for producing fine art digital prints in the early 1990s, and remained popular until the early 2000s (Juergens, 2009).

Despite their popularity, it was quickly discovered that the aqueous, dye-based inks used in the Iris printer were extremely fugitive and sensitive to light and moisture. The earliest prints had a display life of less than three years – far less than that of traditional analogue colour photographic prints – and could bleed on the slightest contact with water (Benson, 2008 and Wilhelm, 2013). This is not surprising, considering that the technology was intended for proof printing, not for creating artworks for display. 

From around 1994, new ink sets with improved lightfastness were introduced, and UV filtering coatings could be applied to the surface to reduce both light and moisture sensitivity (Benson, 2008 and Juergens, 2009). Research has found, however, that the light stability of dye-based Iris ink sets can vary greatly depending on the support used to make a print, and therefore, a later print does not necessarily have improved lightfastness (Wilhelm, 2006).

Iris prints in Tate’s collection

Iris prints are thought to be rare in Tate’s collection. The first I came across was a print by James Welling in our Conservation Archive (Figure 1). I identified just one other from a search on our museum management database (Figure 2), and came across two others by chance (Figures 3 and 4). However, it is entirely possible that more exist that have not yet been identified.

Tate has a thorough accessioning policy when it comes to acquiring new photographic artworks for the collection. A photographic information record (or PIR) questionnaire is sent to an artist or their estate to gather information about the materials and methods used in creating a photographic or digital print¹. The PIR would ideally tell us the exact printing method used in creating a photographic or digital print, and would indicate whether a work was printed using Iris technology. This is an important step in helping conservators to make informed decisions about the preservation of photographic and digital print collections.

Tate started using the PIR in 2014; therefore, for photographs and digital prints which entered the collection before this date, we may not hold as much information about materials as we would like. The Tate collection includes more than 1,000 digital prints, and as more than half of these were printed at the height of Iris printing technology, and not all have PIRs, it seems possible that there may be some Iris prints hidden in the collection. We must look at other ways to identify Iris prints. 

Identification

How can Tate, and other institutions, identify Iris prints in their collections?

PIR – Sending out a PIR when a digital print is being acquired into a collection could flag the type of inkjet technology used to make the print. However, this may not always be accurate, as artists and their estates may not remember or have a record of the exact printing method. 

For prints already in the collection, there are some non-destructive identification techniques:

Date and print characteristics – Fine art Iris prints were produced from 1991 to around 2005, are usually printed on high-quality fine art paper, and will not show differential surface sheen between the inked and non-inked areas (although other fine art inkjet prints can also exhibit this surface finish) (Juergens, 2009). If you have an unidentified inkjet print which was printed around these dates and has these characteristics, then it may be worth investigating further.

Examination under magnification – If an Iris print is suspected, examination at between 10x and 30x magnification will reveal the ink pattern or ‘matrix’ characteristic of a particular printing technology. Iris prints have a regular ink pattern, where the ink dots are laid down by the printer onto the support in a specific pattern, in contrast with other fine art inkjet printing technologies, where the ink dots are laid down either at random or in a linear formation². Useful resources to help identify the matrix of the print in question include the Image Permanence Institute’s online Graphics Atlas³, the DP3 project website⁴ and Martin Juergens’s book The Digital Print: Identification and Preservation (2009), which all provide historical and technological information and photomicrographs of digital prints to help with visual identification. I took my own photomicrographs to compare the matrices of Iris inkjet prints in our collection with the matrix of a ‘drop-on-demand’ inkjet print from a sample set. A regular matrix can be seen in the Iris prints (Figures 5 and 6), in contrast with the irregular pattern of the drop-on-demand inkjet print (Figure 7).

Storage, display and treatment

Correct identification of Iris prints, or any digital or photographic print, ensures that we as conservators are better equipped to preserve our photographic and digital print collections.

For the confirmed Iris prints in our collection, we have created storage mounts using unbuffered museum board, interleaved with photo purity paper (standard practice for all our photographic artworks). They will be stored in the dark in our environmentally controlled cool store, which is dedicated to photographic materials.

In terms of display, we now know that these are some of the most vulnerable prints in the collection, so we can recommend lighting the works for no more than 12 months every decade at an illumination of 50 lux to prevent fading and colour shift⁵. Like with all of our paper-based and photographic works, we will ensure that Iris prints are displayed in a controlled environment at 40-50% RH, which will inhibit any bleeding of the media.

In terms of treatment, any introduction of moisture should be avoided, as it may solubilise the inks, and like for all digital prints, thorough research and testing should be carried out before any conservation treatment is undertaken to ensure that there are no adverse effects to the many different inks and supports.

End note

It was a chance encounter with an unusual print that led me to research Iris printing technology and the presence of these prints in our collection. Any conservator tasked with the preservation of inkjet prints will know that the myriad of technologies, inks and papers used in their creation makes them difficult to identify, and their vulnerabilities can vary greatly. I hope that my experience with these particularly fugitive prints will help to highlight their presence in museum collections, and will raise awareness of the preservation issues associated with them.

Footnotes

¹ For more information about the PIR please see https://www.culturalheritage.org/membership/groups-and-networks/photographic-materials-group/publications/photographic- information-record

² Iris printers used continuous inkjet technology, whereas most other inkjet printers use drop-on-demand inkjet technology. Continuous inkjet creates a regular ink pattern, whereas drop-on-demand creates an irregular or linear pattern, which can help distinguish an Iris print from other inkjet technologies.

³ http://www.graphicsatlas.org/identification/?process_id=93#overview

⁴ http://www.dp3project.org/

⁵ This recommendation is derived from print permanence predictions by Henry Wilhelm, who found that Iris prints displayed at 450 lux, 12 hours per day, at 24 ⁰C and 60% RH could fade noticeably after just two years of display (see http://www.wilhelm-research.com/ist/WIR_IST_2006_09_HW.pdf). These predictions can be extrapolated to advise display parameters for Iris prints displayed at lower light levels, i.e., 50 lux, based on a predicted lifespan of 250 years.

References

Benson, R. (2008) The Printed Picture. New York: Museum of Modern Art.

Juergens, M. (2009) The Digital Print: A Complete Guide to Processes, Identification and Preservation. Los Angeles: Getty Publications.

Wilhelm, H. (2006) A 15-year history of digital printing technologies and print permanence in the evolution of digital fine art photography: from 1991-2006. [pdf] Virginia: IS&T. Available at: http://www.wilhelm-research.com/ist/WIR_IST_2006_09_HW.pdf [Accessed 16.03.2021].

Wilhelm, H. (2013) The Permanence and Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures. [pdf] Iowa: Preservation Publishing Company. Available at: http://www.wilhelm-research.com/pdf/HW_Book_01_of_20_HiRes_v1c.pdf [Accessed 26 10. 2020].

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Jordan Megyery is currently Conservator of Contemporary Art in the Paper and Photograph Conservation department at Tate, where she focuses on photographic acquisitions. She has previously worked on the international loans programme and a large-scale storage and movement project at Tate. Prior to this, Jordan completed a year-long Icon internship in Photograph Conservation and Audience Engagement, sponsored by the Clare Hampson Fund, hosted by both The National Archives, UK and Tate. 

Jordan graduated from the Conservation of Fine Art (MA) programme at Northumbria University, UK, in 2018, where she specialised in the conservation of works of art on paper. During the MA, she was awarded the Zibby Garnett Travel Fellowship to undertake an internship in paper conservation at the Amsterdam City Archives and was also an intern on the Scottish Session Papers digitisation project at the Centre for Research Collections, Edinburgh University Library.