Print Permanence
- An Epson White Paper -

3. Basics of Print Permanence

WIR Print Display Permanence Ratings

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The subject of image stability of color photographs has become considerably more complex in the last decade. In the past, most color prints were produced by labs or service providers using a chemical-based analog process with materials obtained from just a few manufacturers. The number of companies producing traditional sensitized materials remains few, but there are significant print permanence differences in these products that can be measured.[1] Unfortunately few consumers know there are differences and that they have choices.

As photography moved into the digital age and as more companies entered the business, the industry developed predictive print permanence tests that give better insight into how all prints, especially those displayed in light, will look to future generations. But if any manufacturer makes compromises to print permanence testing methods that artificially inflate longevity predictions, a new generation of consumers may see their precious memories fade, just as they have in the past. No photographic print can last forever, but responsible companies like Epson are continually striving to improve the permanence of inks and papers so that photographic prints can last for generations even when displayed and exposed to light.

The past decade has seen a significant increase in the number of images produced with digital printers by both professionals and consumers. The number of output devices has increased dramatically, and the different materials being used vary widely in both their composition and response to environmental factors. To make informed decisions, it is critical to recognize confusing apple-to-orange comparisons and to beware of sweeping claims of universal compatibility. Both may adversely affect image quality or print permanence or both.

The three primary technologies in use today to produce color photographic prints are:

• Traditional Silver-Halide

• Dye Sublimitation

• Inkjet

>Traditional Silver-Halide Color Photographic Prints
Until the 1990s almost all color prints were made with light sensitive materials that incorporated color dyes in an emulsion adhered to a paper which was sealed by a plastic coating. In normal practice, these prints are made by first creating a negative image with a camera and color negative film. The negatives are then used to print a positive image on a silver-halide sensitized paper. A traditional silver-halide color print can also be made from a digital file. Instead of exposing the sensitized paper with white light passing through a negative via an optical enlarger, a laser or an LED exposes the paper. It is important to note that regardless if the print was exposed with a laser or with a traditional optical enlarger, the permanence characteristics of a silver-halide color print remain the same. If stored in the dark, with low humidity, traditional silver halide prints may last from 50 to more than 100 years. If exposed to light, the colors will deteriorate at a more rapid pace. This deterioration will vary widely between manufacturers' products and the levels of illumination and ultraviolet light to which a print has been exposed.[2]

>Dye Diffusion Thermal Transfer Prints (Dye-Sub Prints)
In this process files generated from digital cameras or scanned negatives, transparencies or traditional prints are sent to a printer where heat transfers colorants from a donor ribbon to the final print. Today most dye diffusion thermal transfer printers apply a clear protective layer to the print during the transfer process to ensure water resistance and to prevent smearing and staining when rubbed or handled. This protective layer provides relatively little protection against the effects of light. When exposed to well-lit display conditions suitable for the enjoyment of photographs, the permanence of these prints is generally not very good. [3] Usually claims of exceptional lightfastness for dye-sub prints assume dark storage or such very low light conditions that most people would consider the illumination inadequate for viewing prints.

>Inkjet Prints
As with dye-sub printers, files generated from digital cameras or scanned negatives, transparencies or traditional prints are sent to an inkjet printer. The majority of photo-quality printers use inkjet technology in which very small droplets of ink measured in picoliters (trillionths of a liter) are deposited onto paper. Inkjet print stability varies widely based on the composition of the colorants used in combination with the particular paper selected. Many combinations are available. [4]

Cross-section coated inkjet paper

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[1] See: WIR Display Permanence Ratings for Current Products in the 4x6-inch Printer Category, Wilhelm Imaging Research, Inc., December 7, 2004, available at www.wilhelm-research.com

[2] Henry Wilhelm and Carol Brower (contributing author), The Permanence And Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures, Preservation Publishing Company, Grinnell, Iowa, 1993. This 758-page book is now available in PDF format at no cost from www.wilhelm-research.com

[3] See: WIR Display Permanence Ratings for Current Products in the 4x6-inch Printer Category, Wilhelm Imaging Research, Inc., December 7, 2004, available at www.wilhelm-research.com

[4] See: Anush Yegyazarian, "The Fade Factor," PC World, pp. 18-, San Francisco, California, November 2002, and Dan Littman, "Cheap Ink Probed", PC World, pp. 22-, San Francisco, California, September 2003.