I. Causes of change:
- Instability of the materials
- Faulty application of techniques
- Lime washing and over painting
- Exposure to extremes of humidity
- Water soluble salts
- Exposure to dehydration
- Atmospheric pollutants
- Frost action
- Biological action
- Minor physical causes
- Uncontrolled artificial heating
- Defective restorations
- Changes characteristic of different types of rendering
II. Control:
- Water, the universal catalyst
- Survey and measurement of humidity and temperature
- Instrumentation
- Humidity control