While there has been considerable investigation on the image stability (fade and yellowing) of digitally printed materials, there has been significantly less evaluation of their physical integrity. This is surprising given that an IPI survey of libraries, archives, and museums showed that abrasion and scratch were the number one reported form of damage to digital prints in cultural heritage collections.
The research reported here was focused on investigating the scratch sensitivity of digital prints and comparing those results to a previous study on their sensitivity to abrasion. Scratch occurs when a pointed object of very low surface area, such as the tip of a pin, moves across the print surface creating a gouge. Abrasion occurs when a flat object of relatively large surface area is moved across the surface of the print such as one print on top of another in a stack.
The apparatus described in ISO 18922 was used to scratch prints produced by a wide variety of digital print technologies. The evaluation technique described in the ISO document, however, was found to be ineffective for these materials. Image analysis equipment and software proved more reliable in quantifying the scratch sensitivity. The data showed that the abrasion sensitivity of digital prints cannot be used to predict their sensitivity to scratches and vice versa.
In order to establish a single value that represented overall surface sensitivity to damage, the sensitivities of both the abrasion and the scratch measurements were added. The chart below ranks the combined abrasion and sensitivities for each print category.
Conclusions and recommendations from this study are summarized below:
- There is no correlation between damage to digital prints from abrasion and from scratches. Prints sensitive to abrasion may or may not also be sensitive to scratch and vice versa
- Pigment inkjet (on all papers types), traditional color photography, and black-and-white electrophotographic prints are the most sensitive to damage
- Dye sublimation and color electrophotographic prints were the most resistant to both types of damage
- Clean, smooth plastic sleeves can provide protection. Of course, preventing all contact with adjacent surfaces, such as is achieved with window-matting prints, will be most effective in mitigating damage from abrasion and scratches
The full technical paper outlining the study and its results can be downloaded in PDF format. [2]