In this guide
Three familiar terms carry different amounts of evidence.
“Acid-free” commonly indicates that paper meets a stated acidity or alkalinity condition at manufacture. On its own, it does not describe every fibre, reserve, strength or ageing property, and it does not predict the life of a finished book. Ask which test, specification or mill declaration supports the wording.
ISO 9706:2025 specifies requirements for permanent paper intended for documents. Its scope is unprinted paper and it does not apply to board. ISO 11108:2025 addresses archival paper intended for documents and publications requiring permanent retention and frequent use; it describes archival paper as a special-purpose category. These are defined standards, not casual synonyms for any pleasant uncoated stock.
A mill may also publish a paper-stability declaration for general graphic applications. Retain the exact technical sheet and its date. A reseller’s product title or an undated swatch label is weaker evidence when permanence is part of the purchase decision.
Paper composition and durability need more than a pH value.
Permanence standards consider defined paper properties rather than one marketing phrase. Fibre composition, resistance to oxidation, alkaline reserve and strength-related criteria may be relevant under the applicable specification. Buyers do not need to reproduce laboratory tests; they need a supplier declaration that identifies the named stock and standard being claimed.
Lignin is often discussed in archival buying, but “lignin-free” should not be used as a substitute for documented compliance unless the supplier supports it. Likewise, cotton content, recycled content or a natural shade does not independently establish permanence. Keep each claim attached to its own evidence.
The finished book contains more than unprinted paper.
Ink or toner forms the information and image that must remain legible. Adhesive, thread, endpapers, boards, cover cloth, lamination, foil and inserts introduce other materials. A permanent text paper does not certify the complete object. If a collection has conservation requirements, ask its responsible specialist which components and test evidence belong in the brief.
ISO 11798 covers evaluation of permanence and durability for certain writing, printing and copying on paper in protected environments, with stated limits to its scope. It is not a universal guarantee for photographic colour fidelity or every artistic reproduction. An art book whose value lies in subtle colour may need image-stability expertise beyond a document-retention claim.
Binding remains a physical system. Adhesive suitability, grain, section preparation and handling influence whether pages stay together even when the sheet itself meets a permanence requirement. The PUR and EVA comparison shows why an adhesive name is not a durability promise.
Storage can overwhelm a sound material choice.
Heat, high humidity, water, pollutants, intense light, pests and poor handling can damage documents. ISO 9706 explicitly excludes hostile storage conditions from its intended judgement. A standards claim should never be translated into “lasts 200 years” or another unsupported duration on a customer page.
Describe the likely environment: controlled archive, domestic shelf, public reference room, travelling exhibition or frequently handled family copy. Protective enclosure, shelving, light exposure and handling policies may matter as much as a small difference between candidate papers. The durability and handling brief helps document that physical use.
Put the evidence into the specification and substitution rule.
Name the manufacturer, paper range, finish, shade and grammage, followed by the exact permanence or archival requirement and current technical evidence. If an equivalent may be offered, state which documented properties must remain equivalent. “Acid-free paper or similar” leaves the crucial part undefined.
Keep a physical sample for shade and feel, but do not treat appearance as compliance. At approval, identify the text, endpaper and cover materials separately. A later reprint should revisit the evidence rather than assuming a current paper with a familiar name still carries the same declaration.