HARC Environmental Targets
HARC’s storage environments follow current preservation guidance emphasizing stable temperature and relative humidity bands rather than single fixed points. Targets below are intended as practical ranges for long-term preservation and daily operations.
| Material Category | Primary Use | Temperature Target | Relative Humidity Target | Notes |
|---|---|---|---|---|
| Paper records, books, bound volumes, manuscripts | Long-term storage with regular reading-room use | 60–70°F (15–21°C), stable; seasonal drift kept minimal |
30–50% RH, stable; daily fluctuation < ±5% RH |
Avoid sustained RH above 55% (mold risk) or below 25% (embrittlement). Use archival enclosures to buffer short-term swings. |
| Photographic prints & negatives (B&W and most color) | Primary vault storage with limited retrieval | 40–55°F (4–13°C) where feasible; never higher than general stacks for extended periods |
30–40% RH, very stable | Cooler conditions significantly slow dye fading and vinegar syndrome. Use enclosures specifically designed for photographic materials. |
| Film, slides, magnetic & optical media | Preservation storage; access copies used for research | Cold or cool storage when available: ~35–45°F (2–7°C) for at-risk film; at minimum < 65°F (18°C) for magnetic media |
30–40% RH, tightly controlled | Use separate cold/cool storage where possible. Emphasize digitization and use of access surrogates to reduce handling. |
| Mixed collections (paper, books, some photographs) in shared stacks | General vault / stacks environment | 60–65°F (15–18°C) compromise band, with minimal daily swing |
35–50% RH, stable; avoid rapid swings > ±5% RH/day |
Use archival enclosures and boxes to buffer materials that prefer cooler or drier conditions; segregate especially sensitive media where possible. |
Basis: Targets adapted from NEDCC Preservation Leaflets, NARA 1571 archival storage guidelines, NISO TR01 environmental guidance for paper records, and Image Permanence Institute recommendations for photographic and media storage. Local facility capabilities and risk assessments may refine these ranges.