Understanding Glass Disease and Decay

Introduction Glass disease, also known as sick glass or glass illness, refers to the degradation process of glass that results in various forms of damage such as misting, foxing, blooming, crizzling, spalling, and cracking. This article explores the types, causes, and possible treatments for glass disease.

Types of Glass Disease

1. Misting/Foxing / Blooming.
   • Description: Misting, also known as foxing, appears as a cloudy or hazy layer on the glass surface. It is caused by the leaching of alkali from the glass.
   • Cause: Exposure to moisture or high humidity.
   • Cure: Gentle cleaning with mild conservation detergent and de-ionized water can sometimes remove the surface deposits and slow further deterioration.
2. Crizzling
   • Description: Crizzling is the formation of a network of fine cracks on the glass surface.
   • Cause: The exchange of alkali metal ions in the glass with hydrogen ions from water vapor.
   • Cure: Controlled humidity (40-55%) and air movement can help slow down crizzling. Once crizzling has started, it cannot be reversed, only managed.
3. Weeping
   • Description: The formation of droplets on the glass surface.
   • Cause: High humidity causing alkali to leach and form droplets.
   • Cure: Reducing humidity levels can help prevent further weeping.
4. Spalling
   • Description: The flaking or chipping off of the glass surface.
   • Cause: Advanced stage of glass disease where cracks extend deeper into the glass structure.
   • Cure: No cure exists, but careful handling and controlled environment can prevent further damage.
5. Fragmentation
   • Description: The breaking apart of the glass into pieces.
   • Cause: Severe structural weakening due to prolonged exposure to degrading factors.
   • Cure: Irreversible, but preventive measures like humidity control are crucial.

Causes of Glass Disease

Glass disease is primarily caused by inherent instability in the chemical composition of glass. Factors such as the proportion of silica, alkali, and alkaline earth in the glass affect its stability. Environmental factors like humidity, temperature fluctuations, and exposure to water can accelerate the degradation process.

Conservation and Treatment

1. Washing: For early-stage disease, washing with tepid tap water and a mild detergent can help stabilize the glass.
2. Humidity Control: Maintaining a stable humidity level (40-55%) is essential to slow down the deterioration.
3. Airflow: Ensuring proper airflow around the glass objects can reduce moisture buildup on the surface.
4. Misting: There is a way to remove misting/foxing from glass, I have tried every way possible from steradent tablets or bleach, below are two examples of films where I figured out how to remove it.

There is a way of removing The misting/foxing from glass. I have created a couple of YouTube films for you, the links are below.

Conclusion

Glass disease, while often irreversible, can be managed through careful environmental controls and preventive measures. Understanding the types and causes of glass disease is crucial for the conservation and preservation of glass artifacts.