Display cases may not seem to be obviously important - you may think that the object's visibility to the public is all that matters. There are, however, several more crucial factors to consider when choosing display cases and picking the appropriate case is more complicated than just finding the best price.
Choosing the right kind of display case is part of how you care for your collections and can help to protect your items from the ravages of time.
Different kinds of display case
There are four broad different kinds of display case, each of which we'll describe in this guide and give you guidance on choosing the right one for your collections.
These types are:
- Conservation grades cases
- Ventilated cases
- Standard cases
- Designer-built cases
Conservation grade cases
Conservation grade criteria
Conservation grade cases provide the most protection for items in your collection.
In order 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 less than 0.1 air changes per day
- 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.
Below are a few examples of items that might require such controlled display environments:
- Some metalwork, 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
Even if your item does not require a conservation grade display case, consider purchasing one for its longevity. The quality of the materials and their controllable environments mean that such cases can be used repeatedly in future to display a variety of items. Occasionally, other museums will require you to have conservation grade cases when they lend 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 and makes such cases cheaper than conservation grade equivalents.
What to remember
In order for a case to be properly ventilated, the vents need to be 2 cm long. While vents maintain the airflow, they do also allow dust to accumulate, so the interior needs to be cleaned more. Take great care when removing each item from its case and only clean the case with appropriate materials.
Increased item handling leads to a greater risk of damage.
When to buy ventilated cases
Certain items can survive being displayed in ventilated cases.
Times when it is appropriate to use one include:
- When your item is not 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.
Standard and designer-built cases
If you don't have the funding for conservation grade or ventilated cases, then you can simply use standard or designer-built cases. These are less likely to be as stable and controlled as the more expensive options. The key to getting a standard case is ensuring that you choose one with the right materials.
Materials you can use
Some materials are safe to use in any kind of case.
- Metal, preferably baked enamel or steel on aluminium
- 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 is not ventilated, causing pollutants and harmful chemicals to accumulate.
Materials you should not use in display cases include:
- Many different 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
When not investing in conservation grade display cases, always consult a conservator before buying cases that could potentially damage your collections.
Improving your display cases
It is possible to customise display cases to better control their environments. If you have bought a ventilated or standard case, then add further protective measures to better 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. Don't be tempted to use a lacquer or paint, as they're proven to be far less effective than laminate foil.
Once you have 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 are 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. Many different kinds of 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. Opt for 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. Find a way to vent the heat to avoid all of the problems described above. Alternatively, use fibre-optic lighting, which is much cooler as it carries light from an external source.
Museums Galleries Scotland has plenty of advice to offer anyone running a museum. Read more of our advice guides to learn about lighting, caring for textiles and more.
Other links we think are helpful on this topic include advice sheets from the Collections Trust and the Museums Association's quarterly publication Museum Practice.
For any more questions on choosing display cases, contact us