Effective conservation begins with knowing what an object is made of and how it fails. Most collections are chemically unstable from the moment of manufacture; deterioration is not an accident but the predictable behaviour of materials responding to their environment. Reading those material clues lets a practitioner anticipate risk rather than react to damage.

Deterioration is usefully grouped into the ten agents of deterioration defined by the Canadian Conservation Institute, an internationally adopted framework: physical forces, theft, fire, water, pests, pollutants, light, incorrect temperature, incorrect relative humidity, and dissociation (loss of information or provenance).

Common materials and how they fail

  • Paper - acid hydrolysis and oxidation. Wood-pulp paper made after c.1850 contains lignin and alum-rosin sizing, driving embrittlement and yellowing; foxing appears as brown spots.
  • Parchment & leather - hygroscopic and dimensionally unstable; red rot in vegetable-tanned leather from sulphur-dioxide pollution.
  • Photographic media - silver mirroring, dye fading in colour prints, and the hazardous decay of cellulose nitrate and acetate ("vinegar syndrome").
  • Magnetic & optical media - binder hydrolysis (sticky-shed) in tape; delamination and rot in optical discs. Add rapid format obsolescence.

Inherent vice and the role of environment

"Inherent vice" describes instability built into an object by its own composition - iron-gall ink corroding its paper support is the classic case. Environmental agents accelerate these processes: for many organic materials the Arrhenius relationship means chemical decay roughly doubles for each 5-10°C rise in temperature. Fluctuating relative humidity drives mechanical stress as materials swell and shrink.

In practice. Segregate the "reactive" materials early - cellulose nitrate/acetate film, magnetic tape and colour photographs are chemically ticking clocks. Cold storage and prioritised reformatting buy the most life per unit of effort for these classes.

Key takeaways

  • Identify the material first - its composition predicts its failure mode.
  • The ten CCI agents of deterioration give a complete, internationally recognised risk checklist.
  • Temperature and relative humidity are force multipliers on every chemical decay pathway.

Check your understanding

Last modified: Saturday, 1 August 2026, 10:37 AM