What to monitor
Start with the variables that actually explain the risk.
For this material group, the environmental record is most useful when it captures the things below and keeps them tied to the object, space or display context.
- Relative humidity and rate of change
- Temperature where it drives RH change
- Visible light and display duration
- Local heat from lighting or radiators
- Case, wall and room differences
What can go wrong
The number only matters because of the damage mechanism behind it.
Movement and stress
Wood, canvas and gesso expand and contract as moisture changes. That movement can contribute to cracking, flaking, open joints and distortion.
Light sensitive colour
Some pigments are stable while others fade readily. MGS places many oil and tempera paintings in its 200 lux group, but thinly coloured or particularly sensitive works can fall into lower light categories.
Composite construction
Frames, panels, canvas, grounds, paint layers, varnishes and repairs do not all respond at the same rate. That is why condition and construction matter.
Published guidance
Useful examples, with the caveat kept attached.
Museums Galleries Scotland gives 40–60% RH as a broad example for paintings on canvas. It gives the same broad range for paintings on wood and polychrome sculpture, while stressing that panel construction, wood grain, joins and condition can justify narrower control. Its lighting guide places oil and tempera paintings in the 200 lux group, with more sensitive painted works requiring less.
Where judgement comes in
Panel paintings are specifically flagged by Icon as one of the material groups that can need tighter, specialist RH control. Do not turn the broad 40–60% example into a default for a known sensitive panel without conservation advice.
How this maps to LÆFAN
Keep the reason for the profile with the readings.
Set profiles at the right level: a whole gallery where that makes sense, or an individual case/object context where it does not.
Use rate of change and excursion duration alongside the headline RH band for vulnerable composite objects.
Track light cumulatively for works on display and retain the display period in the record.
Compare case or object conditions with the gallery when you need to understand whether the microclimate is helping.
LÆFAN does not decide the conservation limit for you. It records the profile your institution has chosen, the source or rationale behind it, where it applies and what happened while it was in force.
Sources & further reading
Where the examples on this page came from.
Caring for paintings and frames
Open source ↗Temperature and humidity in museums
Open source ↗Conservation and lighting
Open source ↗Environmental management for collections and climate sustainability
Open source ↗Sources checked 6 October 2026. Guidance and standards can change, so follow the linked publisher page before adopting a value into policy.