On October 25th the Lead Conservator took part in the three-day Digital Print Preservation workshop offered by the Image Permanence Institute in Rochester, NY. This workshop was aimed to teach and inform a group of professionals in the heritage field about identifying digitally printed materials. Once digital prints can be identified it is possible to determine how they should be handled, stored, and exhibited. Also, as some digital prints are more susceptible to water damage than others, it is important to identify the printing processes in the collection to prioritize those for evacuation and treatment.
The Big Three
- Dye Sublimation Print
- Electrophotographic Print
- Inkjet Print
Dye Sublimation Prints rely on the digital print process most commonly used to produce instant photos at Wal-Mart and Shoppers Drug Mart. How can they be identified?
- Sometimes one or two edges are serrated from where the tear-off tabs were removed.
- Photos of this process are most often 4” x 6”.
- If looked at under a microscope or loupe it should not be possible to focus on a particular dot of ink.
- This method is still used to transfer dyes to textiles.
Electrophotographic Prints are created by laser printers and photocopiers and produced with toners not inks. Either dry toner or pigment suspended in liquid may be used. How can they be identified?
- If looked at under a microscope or loupe, amplitude modulation (AM) screening can be seen. This is when the centre of each dot of toner is equidistant from one another, but the size of each dot changes in order to create tonality within the image.
- If liquid toner is used, the edge of the image will not have a clean line. This is because liquid toner cannot produce half dots. If dry toner is used, half dots can be created and the edge of the image will be clean lined.
- Liquid toner produces a more distinct dot than dry toner.
- EP prints often have “satellites” which are random tiny specks of toner that can be found throughout the print.
InkJet Prints are the most commonly produced prints , which can be found on every type of paper including office paper, fine art papers, photo paper, and even canvas. How can they be identified?
- Inkjet prints can be either AM screening or frequency modulated (FM) screening, but are most often FM screen printed. FM screening is when ink dots are applied more densely in areas to create tonality within the image. The dots appear to be randomly placed.
- The ink used to produce these prints can be either dye or pigment based.
- Dye based inks are more easily absorbed into the paper whereas pigment based inks sit closer to the surface of the paper which can make them appear more vibrant.
- Aqueous dye inkjet prints are extremely water soluble and fade quickly, though sometimes a topcoat has been applied over the image to help slow down the rate of discolouration.
Please visit the wonderfully educational Digital Print Preservation Portal to learn about handling and caring for digital prints.
The Lead Conservator extends her thanks to the staff at the Image Permanence Institute for offering such an informative and fascinating workshop, and to the Andrew W. Mellon Foundation for making the workshop possible.