Glossary
Archival safe
Also called: archival quality, archival sleeves
"Archival safe" is a marketing description, not a measurable standard — conservation bodies treat the word "archival" as having no fixed definition.
This is the single most over-used phrase in card supplies, and it is worth being precise about. Preservation guidance is explicit that the designation "archival" is misleading and cannot be used as a standard of measurement. Nothing certifies it and no threshold defines it.
There are real standards underneath. Storage enclosures can be tested against ISO 18902, and the Photographic Activity Test (ISO 18916) measures whether a material chemically harms the item stored in it. A product that cites those has evidence behind it; a product that says "archival safe" has a sentence.
None of this means the products are bad. Dragon Shield's Perfect Fit inner sleeves, for example, describe themselves as "100% archival safe (acid- and PVC-free)" — and the material claim there is polypropylene, which conservation guidance does list as chemically stable. The material statement is the part you can verify. The word "archival" is the part you cannot.
Read the polymer, not the adjective.