ISO 18901:2010

Overview

ISO 18901:2010 - Imaging materials - Processed silver‑gelatin‑type black‑and‑white films - Specifications for stability - defines stability requirements and test methods for photographic films intended for long‑term record storage. The standard applies to safety cellulose‑ester or polyester‑based films with silver‑gelatin emulsions that are processed to produce black‑and‑white silver images by negative or full‑reversal processing. It covers films processed with a thiosulfate-containing monobath followed by conventional wash, and films stabilized by partial or full conversion of silver to silver sulfide, silver selenide or gold. ISO 18901:2010 also addresses films with ultrasonic or dielectric (induction‑heated) splices, while excluding many other film types and processing methods.

Key topics and technical requirements

• Scope and applicability: Specifies which film types are covered (safety cellulose‑ester or polyester bases; silver‑gelatin emulsions) and several clear exclusions (chromogenic black‑and‑white, colour images, magnetic tracks, dry/thermal or diffusion‑reversal processing, films lacquered, or monobaths not using thiosulfate).
• Film base requirements: Identification of cellulose‑ester vs polyester bases and associated life‑expectancy (LE) limitations (some cellulose‑ester films may have LE up to 100 years; some polyester films up to 500 years under recommended storage).
• Processed film properties: Requirements and limits for free acid, residual thiosulfate, residual silver compounds, tensile properties, and loss in tensile strength after conditioning.
• Layer performance: Tests and limits for layer adhesion, emulsion flow, blocking, and thiosulfate concentration in the emulsion/backing layers.
• Image stability: Predictive life expectancy (LE) ratings for radiographic films, microfilms and other film classes, plus image‑stability testing and accelerated‑ageing protocols.
• Test methods: Detailed procedures for base identification, accelerated‑ageing conditions, free acid determination, tensile testing, tape‑stripping adhesion, humidity‑cycling adhesion, emulsion‑flow, blocking, residual silver compound measurement, and image‑stability evaluation.

Practical applications and users

ISO 18901:2010 is used by:

• Film manufacturers for product specifications and quality control.
• Photographic processors and labs to validate processing chemistry and washing procedures (residual thiosulfate control).
• Archives, libraries, museums, and records managers to select and accept film for long‑term preservation.
• Medical imaging departments and radiography equipment suppliers for radiographic film stability.
• Conservation scientists and QA laboratories conducting accelerated‑ageing and image stability assessments.

Benefits include improved preservation of photographic records, predictable life expectancy (LE) ratings, and standardized test methods for production and acceptance testing.

Related standards

• ISO 18902 - Processed imaging materials - Albums, framing and storage materials
• ISO 18906 - Photographic films - Specifications for safety film
• ISO 18911 - Processed safety photographic films - Storage practices
• ISO 18917 - Determination of residual thiosulfate and related chemicals
• ISO 5‑2 / ISO 5‑3, ISO 527‑3 - Density and tensile test references

Keywords: ISO 18901:2010, silver‑gelatin films, black‑and‑white film stability, life expectancy (LE), residual thiosulfate, archival film, processed photographic film, accelerated ageing.