Choosing new display cases

Conservation grade criteria 

Conservation grade cases provide the most protection for items. For a display case to be given this classification, the method of construction and materials should meet the following criteria: 

• Sealed from airflow – the case should have  an air exchange rate of less than 0.1 per day (for more information see this article).
• Built from chemically stable materials, so avoid wood and wood composites such as Medium Density Fibreboard (MDF). 
• The possibility of relative humidity control to create micro-climates. 
• No internal heat sources such as lighting.

When to choose conservation grade cases 

Conservation grade cases are essential for any items that require tightly controlled environments. This applies especially in rooms where environmental factors fluctuate, such as in museum foyers or city-centre buildings. These sealed cases protect items against shifts in relative humidity and air pollution.

Examples of items that might require controlled display environments include: 

• Some metalworks, especially archaeological artefacts 
• Some composite objects 
• “Weeping” glass 
• Weak or deteriorated objects
• Organic materials, such as wood from archaeological finds 
• Chemically unstable items, such as celluloid nitrate or geological specimens

This list is not exhaustive and if you are in any doubt about items from your collection, contact a conservator. 

Long term investment 

Conservation grade cases are extremely durable and due to the quality of their material and controllable environments, they can be used to display a variety of items. Museums may request that you use a conservation grade case when lending you items from their collection.

Ventilated cases are deliberately unsealed to allow a constant airflow through the case. This prevents the accumulation of pollutants around the item. Ventilated cases are generally cheaper than conservation grade equivalents. 

For a case to be properly ventilated, the vents need to be 2 cm long. While vents maintain the airflow, they also allow dust to accumulate, which means the interior needs to be cleaned regularly. Take great care when removing each item from its case and only clean the case with appropriate materials, which will not cause damage to objects displayed within the case.

Increased item handling leads to a greater risk of damage. 

When to buy ventilated cases 

Appropriate circumstances for using a ventilated case:: 

• When your item isn’t sensitive to relative humidity fluctuation, pollution or dust, such as objects made from glass, stone, and ceramics.
• In indoor environments where the conditions are already monitored and controlled, using air conditioning and other methods.
• If you have trained collections care staff.

Customised cases 

If you don’t have the funds available for conservation grade or ventilated cases then standard or designer-built cases are the next best thing. Standard cases come in a range of materials and it’s important to choose the right one for your collection. 

Materials you can use

Some materials are safe to use in any kind of case.

These include: 

• Metal, preferably baked enamel or steel on aluminium 
• Glass 
• Perspex
• Neoprene, which is used to seal cases 

Others can be used, but only upon consultation from conservators.  

Check before using: 

• Woods such as yellow pine, spruce, walnut, elm or magnolia
• Acrylic latex emulsions and epoxy resins 
• Hot melt glues (ethylene/vinyl acetate copolymer types) 
• Some new polymer boards, tested for stability by independent laboratories 

Materials to avoid

Many materials are too chemically unstable and will react badly against items from your collection. This problem is compounded if the case isn’t ventilated, causing pollutants and harmful chemicals to accumulate. 

Materials you should avoid using in display cases include: 

• Many kinds of wood, including oak, teak, and more 
• Most composites, such as plywood and Medium Density Fibreboard (MDF 
• Adhesives and sealants containing acetic acid or formaldehyde

 Always consult a conservator before buying cases that could potentially damage your collections.

It’s possible to customise display cases to better control their environments.  If you’re using  a ventilated or standard case, then you can use additional protective measures to effectively preserve your items. 

Using laminate foil 

If your case is built from wood, cover it in laminate foil. This seals out damaging materials such as organic acids and formaldehyde.  Avoid using a lacquer or paint, as they’re proven to be far less effective than laminate foil. 

Once you’ve re-sealed your case with laminate foil, you can add pollution absorbers and humidity buffers. If you haven’t sealed the case properly then these additions will be ineffective against high air exchange rates. Pollution absorbers act like sponges and will get saturated quickly if they’re used without proper sealing. 

Move light sources 

Ensure that none of your display cases have interior lighting. In-case light sources quickly ramp up the temperatures and drastically change the relative humidity. Objects can be badly damaged by fluctuating temperatures and humidities. 

The rising heat also changes pressure within the case, which increases air exchange and could bring in dust. Use external lighting to avoid these problems. 

If you require interior lighting, separate it from the main body of the case with a glass or chemically stable barrier and find a way to vent the heat. Alternatively, use fibre-optic lighting, which is much cooler as it carries light from an external source. 

For more information on collections care, see our other advice guides.  

See advice from Collections Trust, who have further information on preserving your museum’s collections.