Storage Recommendations

A variety of harmful forces can affect collection objects in storage resulting in multiple forms of damage. For digital prints, the primary drivers of deterioration in storage are heat, moisture, and air pollutants, though each print type has its own unique sensitivities. Signs of decay include image fade, paper yellowing, ink bleed, and cracking or delamination of paper layers. Tables 1 and 2 show the types of damage that can result from each environmental factor on two broad categories of digitally-printed collection objects: photographs/fine art and documents/books. Control of temperature, humidity, and air quality can significantly extend the usable lives of these materials.

Table 1. Risk Factors For Digitally-printed Photographs and Fine Art

It should be noted that the sensitivities of digitally-printed photographs and fine art to damage are highly variable and product dependent. At times the behavioral differences between individual objects within a particular category are greater than those between categories. For example, photographs printed with two comparable dye inkjet printers using similar ink and paper types can have radically different deterioration rates due to subtle variations in colorant and paper formulations. For this reason, these objects should be treated as individually as possible with condition assessments made on a regular basis.

Table 2. Risk Factors For Digitally-printed Documents and Books

Damage to digitally-printed documents and books will mostly be in the form of paper yellowing. Because these objects are usually maintained for their information content as opposed to aesthetic value, some yellowing may be considered acceptable over long periods as readability will be maintained. For these objects, room temperature storage will suffice. For objects of high value, rarity, or on papers containing recycled materials or groundwood, cool to frozen storage will reduce yellowing rates helping to maintain the object’s original appearance.

Temperature and Humidity Recommendations

As with most collection materials, temperature and relative humidity (RH) drive the natural aging rates of digital prints. Extremes of either can cause significant damage that might not occur under proper storage conditions. IPI data has shown that, in the absence of pollutant gases, digital printing inks, dyes, and toners are fairly robust at room temperature and moderate humidity. However, many of the photograph and fine art inkjet printing papers can be prone to significant yellowing and deterioration of the ink receiver coatings. Lower temperatures can reduce these rates of decay. For this reason IPI recommends low-temperature storage for both dye and pigment inkjet photographs and fine art. For documents and books, some slight yellowing may be tolerated so room conditions will be sufficient. If yellowing would not be acceptable then cool to frozen storage is recommended.

The recommended maximum storage temperatures and relative humidity ranges for digitally-printed photographs and fine art are shown in Table 3. The recommended maximum storage temperatures and relative humidity ranges for digitally-printed documents and books are shown in Table 4.

Table 3. IPI’s Recommendations for Digitally-Printed Photographs and Fine Art Storage

Table 4. IPI’s Recommendations for Digitally-printed Document and Book Storage

*For objects of high value, rarity, or on papers containing recycled materials or groundwood, a temperature of 4°C (40°F) at 30-50% RH may be used to minimize yellowing.
 

Humidity Extremes and Inkjet

High humidity should be avoided to prevent blocking, ferrotyping and mold growth. Inkjet dyes can also bleed severely when exposed to high humidity causing noticeable image blurring and color fringing. The graph below shows the time to bleed for a susceptible inkjet print at 25° C (77° F).  All conditions to the right of or above the line should be avoided. Prints should be safe below 65% RH. However, time to bleed rapidly diminishes as RH increases. Prints at 80% RH or higher can show noticeable bleed in less than 24 hours.

Very low humidity should also be avoided as it can exacerbate brittleness of some inkjet print layers making handling more risky. Like traditional photographs, digital prints should always be handled in RH conditions above 25%. This will be especially true for prints that have been on display because light and pollution exposure can further increase the brittleness of surface layers over time.

Simplified Multiple Media Storage 

Since few institutions can provide special storage areas solely for digitally-printed materials, these objects will need to be integrated with other collection assets. Fortunately, the basics of traditional paper and photograph care can, with a few exceptions, be applied to digitally-printed materials. The IPI Media Storage Quick Reference (MSQR) provides strategies on thoughtfully merging multiple traditional media types into four or fewer common storage conditions. This approach can be extended to include digitally-printed materials. The MSQR is available free for download from IPI.

Table 5 provides qualitative ratings for each material at each storage condition and Table 6 defines the rating system. The temperatures in Table 5 correspond to general storage categories from the IPI MSQR. These tables can be used to answer the fundamental questions: Are our current storage conditions adequate for digitally-printed materials?Or if not, what new environment would be optimal?

Table 5. Mixed Media Collections