What are the differences between the various types of glass?
Tempered glass is made to be strong, durable and impact / scratch resistant through a process called “air quenching.” The glass is pre-cut and edged, placed into a tempering furnace, then cooled rapidly by a system of air jets. The quenching process makes the tempered glass about 4-5 times stronger than non-tempered glass of the same size and thickness.
If tempered glass does happen to break, it does not typically break into shards with sharp edges like regular glass. Rather, it will break into small, rounded pieces and is therefore used in environments where human safety a priority. Tempered glass usually carries a smaller price tag than laminated glass.
Laminated Safety Glass
A good analogy for laminated glass would be that of a glass sandwich. Two (or more) layers of glass are joined together by a translucid plastic vinyl interlayer, which is commonly called PVB (polyvinyl butyral).
One of the benefits of laminated glass is that if it breaks, it sticks to the PVB layer rather than shattering into small pieces. Keeping this structural integrity not only helps to avoid a big mess, it is also a big safety benefit for the surrounding people and objects. The other important benefit is that the PVB layer can block up to 99% of the UV rays.
Low Iron Glass
"Low-iron" is an option available with both tempered and laminated glass. Reducing the iron content in the glass will give it an extra clear appearance without the dominant light greenish tint observed in regular glass.
Low-iron glass, also called extra-clear glass, provides excellent light transmittance in all thicknesses. It is more transparent and more neutral in colour. Low iron glass will provide better color rendition for the displayed objects and is highly recommended in brighter and lighter environments.
Anti-Reflective glass is coated on the outer surfaces with a thin coating that helps light pass through the glass and not get reflected away from it. Regular uncoated glass transmits about 91% of the light through it, with about 8% of the light reflecting back (the rest is absorbed). Coating the outer surfaces of the glass can reduce the amount of light reflected from 8% to 1 or 2%. This is a noticeable improvement in two ways. First, there is less glare or reflection off the glass, allowing you to look through the glass easier. Second, light actually goes through the glass, making everything look brighter.
Anti-Reflective coating is a premium option that is only offered on low-iron laminated safety glass.
What defines museum-quality display cases?
Museum-quality display cases are far more than simple glass enclosures to display your artifacts. Their ultimate role is to Present, Preserve and Protect your sensitive and valuable collections, which can only be achieved through a precise and sophisticated design and construction methodology.
Museum-quality display cases are built using only archival and non-off-gassing materials, which is perhaps the most important characteristic. They also offer airtight display enclosures with low air exchange rates to eliminate the need for maintenance and provide passive or active micro-climate environments. Their designs, which are often customized to specific needs and requirements, may integrate high-end lighting systems along with concealed opening and high-security locking mechanisms. Advanced security and monitoring equipment are also available.
Why should I choose museum-quality display cases?
Providing a properly controlled and stable environment is critical to the long-term preservation of the museum’s artifacts. The major environmental factors that affect their preservation are light, temperature, relative humidity, air pollution and pests. Sophisticated HVAC systems can be quite expensive and may be hard to install without destroying the historical integrity of some buildings.
Museum-quality display cases can be a great alternative while allowing you to present groups of similar objects with their own specific microclimate requirements, so that the air in the rest of the room does not have to be conditioned so stringently.
Micro-Climate Control: What does it mean exactly?
A micro-climate is generally the condition inside an enclosed space, since it differs in temperature, humidity and air cleanliness from the surrounding ambient.
Microclimate display cases are archival and airtight enclosures that offer the possibility to enlarge and reduce the exposition volume and to vary its thermal capacity, the water adsorption capacity and the airtightness to obtain different microclimate settings. The required parameters for a museum display case are a constant, non-cycling level of relative humidity that is maintained with the conservator’s set parameters. The environmental conditions controlled inside the cases can be achieved through active systems and/or through passive systems.
What are passive vs active climate controls?
Climatic control inside the display cases can be achieved through passive or active systems. Passive systems focus on the stabilization of the internal case conditions via a suitable airtightness and a layer of desiccant, usually silica gel, that buffers the environment by absorbing or releasing moisture as necessary.
Active microclimate uses mechanical devices rather than buffers to control and stabilize the internal conditions to a set point value. Mechanical methods include the use of humidifiers, dehumidifiers, air purifiers and more. Active devices have far greater treatment capacity than passive solutions, and are often used on larger display cases, multiple display cases or where passive control is not an option.
Why are relative humidity (RH) and temperature so important?
Fluctuation is what causes the most damage. Objects made of organic materials swell and contract according to the temperature and humidity levels and can suffer irreversible damage when exposed to such fluctuation.
Objects themselves are rarely directly affected by temperature. Fluctuating heat, however, can cause changes in humidity which may damage sensitive objects through RH fluctuations. This is the main reason for controlling the temperature.
Different types of collections have substantially different relative humidity requirements and so it’s difficult to give specific set-points that works for all objects.
What is the air exchange rate (AER)?
The air exchange rate (AER), also known as the air leakage rate, is a measure of how many times the air within a specific enclosure is replaced every day (AER/d). Having an enclosure with a low AER is the best way to minimize the effect of the external climate and to reduce the amount of desiccant needed.
A well-designed glass and a metal display case can easily reach an air exchange rate as low as 0.3 per day. Display cases with leakage rates of one air change every ten days (0.1/d) is now achievable through a combination of high-end technologies, unique sealing and design approaches.
What are Oddy-Tests?
The Oddy test is a procedure created by a conservation scientist to test gasses emitted by a material in a sealed environment. Some materials release volatile components, which, in an enclosed space, may reach levels of concentration capable of damaging the artifacts.
This test consists in placing the material in an airtight enclosure with different metals. After the testing period, if the metal samples show no signs of corrosion, then the material is deemed suitable to be placed in and around museum artifacts. The Oddy test is not a contact test, but is for testing off-gassing.
Are your cases suitable for temporary exhibitions?
Zone Display Cases products are built with durable and sustainable materials for long lasting products. The cases purchased from us will serve your exhibit needs for several decades. Therefore, it’s important to make a thoughtful decision when choosing your display case as it may be used for different needs and configurations over the years.
Most of our cases are collapsible, storable and movable. We also offer customized storage and moving solutions. Although wall cases are not as versatile as freestanding and table cases, they can still be moved if your exhibition plans change in the future.
Are your display cases easy to operate and maintain?
Every case that we deliver comes with a complete and customized maintenance guide. Unless otherwise specified, all our cases are supplied with easy locking and opening mechanisms that can be operated by a single person, no matter how large your cases and doors are.
Our cases are completely airtight and dustproof to eliminate the need for internal maintenance. There is no need to purchase specialty products to clean the exterior surfaces of our cases. We will provide cleaning recommendations based on your selected materials and finishes.
What is the warranty on our products?
Zone Display Cases is proud to offer a 5-year limited warranty on all our permanent museum quality display cases, should they be standard products or custom-built cases installed by Zone or delivered fully assembled.
*Some exclusions apply.
We commit to repair or replace any defective parts, at no cost. This warranty does not apply to damages resulting from accidents, misuse or negligence. Any modifications or alterations of our products without our prior approval will automatically void the warranty.
Please contact us to learn more about our warranty policy.