Chemlights do expire. However, it is important to consider the factors and conditions that bring about their expiration date. These include the chemicals housed within the tube, the material comprising the outer and inner casings, the integrity of the wrapper, and the storage environment.
This article will explore why chemlights have expiration dates printed on them and, more importantly, what contributes to their degradation over time.
Understanding How a Chemlight Functions
It is important to have a basic understanding of how they function to understand how and why chemlights degrade over time.
Every chemlight consists of at least two chemicals within a base solution contained in a sealed tube. The two chemicals are kept separate by housing one in a smaller brittle container within the larger outer flexible container.
When the stick is bent, the inner container snaps and this releases the chemical contained within it so that it comes into contact with the other chemical within the base solution. This creates a reaction that results in chemiluminescence. This is the scientific term for light being emitted as a result of a chemical reaction.
By understanding the basic components of a chemlight stick, it is easier to understand why, over time, their effectiveness can become compromised.
How Are Expiration Dates for Chemlights Determined?
The majority of chemlight manufacturers provide a suggested time frame for optimal usage based on the date of manufacture. These can be up to five years in duration. However, it is not uncommon for a chemlight stick to be effective for considerably longer periods.
This happens because the degradation of chemlights is mainly attributable to the degradation of the outer or inner containers and not the chemicals themselves. Improper storage or extreme temperature and moisture shifts over time can lead to this type of casing degradation.
Likewise, if the chemlight stick is stored at optimum conditions, it can remain effective beyond the manufacturer’s printed expiration date.
To an extent, even the protective wrapper or sheathing that houses an individual chemlight stick could impact its shelf life. If they are improperly sealed, and extreme storage conditions are present, usefulness beyond the expiration date may not be likely. This is why high-end and military-grade chemlights are commonly wrapped in foil to ensure maximum protection against moisture and light exposure.
In other words, the more stable the long-term storage environment for chem lights, the greater the possibility of extending their useful shelf life.
Factors That Affect the Shelf Life of Chemlights
To get the most shelf life out of chemlights, they must be stored as recommended by their manufacturer. This usually involves using a dry, dark, and uncluttered location. However, this is not mandatory and I often carry chemlights free from the manufacturer packaging. The point is it could degrade the shelf life as well as the following factors.
Moisture
When exposed to excessive moisture for prolonged periods, water molecules can penetrate through the outer plastic casing of a chemlight stick. This can adversely affect its operation when needed.
Moisture can accumulate if chemlights are stored in humid environments. It can also occur during condensation when there is a rapid shift in temperatures. This is why they should be stored in a dry location with a cool and consistent temperature.
Most chemlights are labeled as being waterproof. However, this moniker refers to the chemlight stick being usable in wet and underwater conditions once activated. It is not meant to be taken as an acceptable form of storage.
Excessive Exposure to Light
If chemlight sticks are constantly exposed to light, especially sunlight, with its UV rays, the casing can degrade at the microscopic level allowing air and moisture to penetrate over time. This can then negatively impact the chemlight’s luminescence when activated.
Higher-end chemlight sticks, such as the Cyalume ChemLight Military Grade Chemical Light Sticks, are specially wrapped in foil wrappers specifically designed to keep light and moisture out.
However, if you purchase lower-end models, these may come in simple plastic wrappers. Greater care needs to be taken with those types of chemlight sticks to protect them from the light and prolong shelf life.
Purchasing chemlight sticks individually wrapped is an effective method for minimizing needless light exposure to your stock of emergency lighting supplies.
Physical Damage
A chemlight stick that has been crushed by a heavy item during storage or one that has been dropped from a high shelf could experience physical damage that would curtail its storage life, regardless of the expiration date printed on the wrapper.
The force of the weight or the fall could break the inner casing releasing the chemical before it was intended to be used rendering it useless. It could also cause minor damage that over time can allow air or moisture to penetrate the stick and degrade it faster.
This is why chemlight sticks should be stored in rigid containers with a lid to protect them from such damage. Also, for chemlight sticks that you actively carry as part of a mobile emergency kit, make sure that they are secured and protected from other heavier items in your kit. A small rigid container cushioned with shop towels or paracord makes a great travel container for chemlights.
Risks Associated With Using Chemlights Past the Expiration
There are two types of risks associated with using chemlights beyond the manufacturer’s expiration date. First, the brightness and duration of the lighting that they provide can be reduced. Second, the potential exposure to health hazards when using a chemlight stick with its structural integrity is compromised or degraded (however minimal it may be).
- Reduced duration and brightness: If moisture or air has managed to penetrate the outer casing, the presence of these external elements within the base liquid can deter the luminescence of the stick when both chemicals react with each other. In extreme cases, it can result in the chemlight not functioning at all.
- Potential toxic hazards: If a chemlight stick has been damaged or its protective wrapper and casing have degraded sufficiently over time, the base liquid and chemicals housed within it could leak. These can be toxic if swallowed and can cause skin and eye irritation if they come into direct contact with the body. You should consult the material safety sheet for your brand and model of chemlight stick for specific toxicity risks.
How to Extend the Viability of Chemlights Beyond the Expiration Date
It cannot be formally recommended to use equipment, especially when it is slated for emergency and survival gear, beyond the parameters recommended by the manufacturer. If you feel compelled to extend the shelf life of your chemlights, a few steps should be followed regarding storage:
- Keep the chemlights in their wrappers until they are to be used.
- Store the chemlights in a dry and cool environment.
- Keep the chemlights inside a box or in a darkened environment.
- Chemlight sticks that are kept in bug-out bags, vehicles, or any other area where they are subject to constant shifting and fast-changing environmental conditions, should be checked more frequently.
It is important to mention that if a chemlight stick has been damaged during storage for any reason, it should be cautiously inspected for damage regardless of how far off it is from its expiration date.
Conclusion
As explained earlier, chemlights come with expiration dates based on the date they were manufactured. With that being said, it is possible to extend their useful shelflife.
In doing so, however, it is important to be aware of how they function. This will allow you to store them in optimum conditions and possibly get more life out of them.
Even so, if you want to ensure that your survival and emergency gear is always ready to function at an optimal level of readiness, it is best to adhere to the expiration dates posted on chemlights by their manufacturer.