When you’re spending the time to create a custom picture frame and preserve a print or piece of artwork, you want to make sure that you’re getting all the right materials. But with all these terms — archival, museum-quality and photo-safe — it may be confusing to know what they all mean.
The Terminology of Conservation Framing
There are a number of terms that are used when describing picture frames and their various materials: acid-free, archival, conservation quality, and museum-quality, to name a few. While these terms can be useful to convey certain characteristics of the products you’ll be using, these aren’t legal or standardized terms, according to the Image Permanence Institute.
One terms that the IPI uses itself, however, is photo-safe. This term means that the picture framing supplies comply with ISO 18902, the international standard that outlines the requirements for album, storage and picture framing materials that prevent damage to printed images.
The Photo-Safe Tests
ISO 18902 covers all types of picture framing materials, including paper and paperboard (i.e. mat board and mounting board), plastic, metal, adhesives and tapes, glazing, and more. Each type of material has its own requirements, so mat board won’t necessarily follow the same “rules” as an adhesive, for example.
A number of tests can be carried out to ensure that the material complies with the restrictions:
Photographic Activity Test (PAT)
A requirement for all framing materials, the Photographic Activity Test, commonly known as the PAT, is also its own international standard (ISO 18916). There are two types of this test: the Standard PAT (Black & White) and the Color PAT (Dye Coupler Reactivity), the latter of which is always tested alongside the Standard.
This test determines whether there are any chemical interactions between the picture framing material and a photograph. The material is placed in an incubator with controlled temperature and humidity, which simulates aging. Two detectors are used: one tests for oxidation and reduction reactions, which cause fading, spots and silver mirroring, while the other tests for chromophores, which cause yellowing.
pH and Alkaline Reserve Tests
The pH test determines whether the framing material — generally a paper product such as mat board or mounting board — is acidic, neutral or basic. Acid is a natural enemy of art, so this test can be of utmost importance, and it is used for both paper products as well as adhesives. The test is straightforward: a sample of the material is soaked in distilled water, and then the pH is measured.
The alkaline reserve test measures the percentage of alkaline reserve of the paper, meaning how much acid it would take to neutralize the alkaline buffering. Paper-based materials must have an alkali reserve of at least 2% calcium carbonate to pass this test.
Kappa Number Test (Lignin Content)
The Kappa Number Test will show the level of lignin in the paper product. Lignin produces acid, so ensuring that the level of lignin is not excessive helps determine how long the print can last when in contact with a certain framing material.
With this test, the paper product reacts with potassium permanganate; afterwards, the amount of permanganate is measured. The more lignin in the product, the less potassium permanganate there will be left. These tests are only used on paper products.
Colorant Bleed Test
This test is used on colored paper-based products and labeling materials, as they use dye or pigments that can spread to other materials when in contact with water. With this test, the paper or labeling material is pressed against bond paper in distilled water. Afterwards, the bond paper is examined to see how much of the dye or pigment transferred to it.
Additional Photo-Safe Requirements
There may be other requirements for certain materials beyond these tests to ensure they’re still photo-safe, and they can be pretty specific. Adhesives, for example, cannot be rubber-based, while paper products such as mat board cannot be made of post-consumer recycled paper. Plastics — such as those used in photo corners — must not contain plasticizers or chlorinate, nitrate or acetate plastic.
Many of the products that Frame Destination has determined “archival quality” or “museum grade” pass at least one of these tests. Some manufacturers have had their own products tested to be able to call them “photo safe,” such as Lineco’s photo corners, but you should always read the fine print if you’re planning to preserve your prints.