If a particular material or product meets the requirements of this ISO standard there is no assurance that subsequent lots will have the same physical qualities or contain ingredients of the same chemical inertness. All materials or products shall therefore require annual evaluation and testing according to this International Standard, unless the specific lot of materials or products was previously tested. All materials shall also be retested according to this International Standard if the formulation or any component supplier changes. ISO 18902:2013 Imaging materials — Processed imaging materials — Albums, framing and storage materials
One test at the time of product introduction does not ensure quality. While it is better than no tests, the fact is that manufacturers, vendors, and suppliers are continually changing their materials, formulations, and manufacturing processes. Only a process that continually monitors product performance can truly ensure product quality. Yet, given the large number of products, raw materials, and production lots that most manufacturers deal with, continuous testing rapidly becomes impractical.
As a compromise between never retesting a product and continually retesting products, the International Organization for Standardization (ISO) settled on an annual retest requirement in ISO 18902. This requirement requires products for photographic storage, including scrapbooking materials, to be retested annually or when known changes to the production process take place. This requirement helps ensure that products will remain photo-safe over time.
Unfortunately, many manufacturers still ignore this requirement, run a test once, and ten years later are still using this test result to claim photo safety, even though much may have changed during that ten year time period.
The next time you see a product claim, like photo-safe, acid-free, fade-resistant, or archival, ask when the test was carried out. If the test is more than a year or two old, the manufacturer’s words are probably not not worth much.