Why Air Exchange Matters in Glass Display Cabinets: Protecting What’s Inside
When we look at a beautifully arranged glass display cabinet—whether in a museum gallery or a private collection—it is easy to focus on the objects themselves. Behind the scenes, however, one of the most critical factors in preserving those objects is invisible: air exchange.
Air exchange refers to the movement of air between the inside of a display cabinet and the surrounding room. While the concept is simple, its implications are significant. Ventilation affects dust accumulation, humidity stability, off-gassing behaviour, and the overall reliability of the cabinet’s internal microclimate. Selecting the appropriate air-exchange strategy—and ensuring it performs as specified—is fundamental to long-term collection care.
Naturally Ventilated vs. Sealed Cases: What’s the Difference?
Not all display cabinets are designed to perform in the same way. One of the earliest decisions faced by designers, conservators, and specifiers is whether a cabinet should be naturally ventilated or effectively sealed. Each approach offers advantages depending on object sensitivity and ambient conditions.
Naturally Ventilated Cases
Naturally ventilated display cabinets allow a controlled level of air movement between the case interior and the surrounding environment.
Why this can be beneficial:
- Pollutant dissipation: Many construction and display materials—such as wood products, paints, adhesives, and some plastics—release small amounts of pollutants over time. In a sealed environment, these can accumulate to damaging levels. Ventilation allows these pollutants to disperse.
- Low complexity and maintenance: Because they rely on passive airflow, naturally ventilated cabinets typically require fewer internal buffering materials and less long-term intervention.
The main limitation is that naturally ventilated cases are more strongly influenced by the surrounding room conditions. Rapid changes in temperature or relative humidity outside the cabinet can be transmitted inside with relatively little delay.
Sealed Cases
Sealed display cabinets are designed to restrict air movement as much as possible, creating a controlled and comparatively stable internal environment.
Key benefits include:
- Environmental stability: Reduced air exchange buffers objects from short-term fluctuations in temperature and relative humidity.
- Microclimate control: Sealed cases work effectively with desiccants or integrated climate-control systems, enabling predictable long-term humidity control.
However, a sealed cabinet is not automatically a better solution. If internal materials are not carefully selected and tested, pollutants can become trapped. In addition, a case that is described as “sealed” may still allow significant air leakage if it is poorly engineered or inadequately sealed.
Why Air-Change Rates Matter
When sealed cases are specified, defining a measurable air-change rate becomes essential. This rate quantifies how much external air enters the cabinet over a given period and provides an objective measure of airtightness.
The Arts Council recommends requiring independent performance certification after installation. Accredited test houses can measure air leakage and confirm that the cabinet meets the specified performance criteria.
Only once this certification has been provided should the cabinet be formally accepted and paid for. This requirement protects both the collection and the institution’s investment by ensuring that the cabinet performs as designed rather than as assumed.
The Role of Seals: Small Components, Big Impact
Seals around access panels, doors, and joints play a decisive role in determining air exchange. Different conservation strategies require different sealing approaches.
- Brush seals: Effective for reducing dust ingress while still allowing air movement. They are not airtight and are best suited to naturally ventilated cabinets.
- Ethoxy-silicone seals: Used where significantly reduced air exchange is required. These seals support low air-change rates and contribute to stable internal humidity conditions.
Selecting the correct seal ensures that the cabinet’s intended ventilation strategy is actually achieved in practice.
Why Air Exchange Should Never Be an Afterthought
Air exchange influences nearly every aspect of preventive conservation within a display cabinet. When properly specified and executed, it:
- Protects objects from damaging humidity fluctuations
- Limits dust accumulation
- Prevents the build-up of internally generated pollutants
- Supports long-term preservation strategies
- Improves the reliability and quality of exhibitions
Whether you are a museum professional, display-case fabricator, or private collector, understanding air exchange enables informed decisions about the environments in which objects are housed. It is an invisible parameter with long-term, visible consequences.
