Discover essential insights on silica gel’s longevity. Silica gel is an effective and widely used desiccant for protecting products and equipment from moisture and humidity but one of the most common questions when using silica gel is: how long does silica gel last?
Many people often wonder, how long does silica gel last? This is a common query as it relates to effective moisture control in various applications. Understanding how long does silica gel last can help you make informed decisions about its usage and effectiveness. There isn’t one set lifespan for silica gel. How long it remains effective depends on several factors, including the amount of silica gel being used, the size of the enclosed space, humidity levels, the packaging material and how often the package or container is opened.
When correctly sized and used in a properly sealed environment, silica gel can provide effective moisture protection for extended periods.
How Does Silica Gel Work?
Silica gel is a porous, granular form of silicon dioxide (SiO₂) that works by adsorbing moisture from the surrounding air.
Although “absorb” is commonly used when talking about desiccants, silica gel technically adsorbs moisture. This means water molecules adhere to the large internal surface area created by millions of microscopic pores within the silica gel. Under optimal conditions, Pro-Ex silica gel can adsorb up to approximately 30% of its own weight in moisture, although actual adsorption capacity may be lower depending on the conditions in which it is used.
By controlling moisture within an enclosed environment, silica gel can help protect moisture-sensitive products against mould, corrosion, spoilage, clumping and other forms of moisture damage.
So, How Long Does Silica Gel Last?
When silica gel remains sealed in its original packaging and is stored correctly, it can last for years. Once silica gel is exposed to air, there isn’t a single timeframe that applies to every application. Its lifespan will depend on the amount of moisture it needs to adsorb and the conditions in which it is being used.
Factors that can affect how long silica gel remains effective include:
- The amount of silica gel being used
- The amount of air within the packaging or container
- Humidity and air exposure
- Temperature and environmental conditions
- How well the package or container is sealed
- How frequently the package or container is opened
A silica gel sachet inside a well-sealed package may therefore remain effective considerably longer than the same sachet exposed regularly to humid air.
Does Unused Silica Gel Expire?
When stored correctly, silica gel can have an almost indefinite shelf life. However, silica gel starts adsorbing moisture when exposed to the surrounding air. Unnecessary exposure before use can therefore reduce the amount of moisture it is able to adsorb once placed into the intended application.
Pro-Ex recommends keeping exposure to air as short as possible, with sachets exposed for a maximum of 30 minutes before being placed into the product.
How Should Unused Silica Gel Be Stored?
Unused silica gel should be kept sealed and airtight until it is required. Only remove the amount of silica gel you need and reseal the remaining product promptly. Minimising exposure to ambient air helps preserve the silica gel’s available adsorption capacity for when it is actually needed.
Silica gel sachets are ready to use straight from their packaging and do not require preparation before use.
Does Temperature Affect Silica Gel?
Yes. Temperature is an important consideration when using silica gel.
Silica gel performs best in a stable environment. Its adsorption ability decreases at temperatures above approximately 30–40°C. While some moisture can still be adsorbed at higher temperatures, previously adsorbed moisture may begin to be released again. For this reason, Pro-Ex silica gel sachets are not recommended as shipping desiccants where temperatures above 40°C may occur. They are better suited to smaller packaging applications and environments where the risk of high temperatures is low.
For shipping containers and other high-temperature applications, a different type of desiccant may be more suitable.
How Do You Know When Silica Gel Is Saturated?
Standard white, non-indicating silica gel does not change colour when it becomes saturated, making it difficult to determine its condition simply by looking at it. For applications where a visual indication is useful, Indicating Silica Gel may be a better option.
Pro-Ex offers two types:
- Orange Indicating Silica Gel changes from orange to green as it becomes saturated and is suitable for food applications.
- Blue Indicating Silica Gel changes from blue to pink as it becomes saturated. Blue silica gel contains cobalt chloride and is not suitable for use with food products.
The colour change makes it easier to determine when the silica gel needs to be replaced or reactivated.
Can Silica Gel Be Reactivated and Reused?
Yes. Silica gel can be reactivated by removing the moisture it has adsorbed. For Pro-Ex Indicating Silica Gel, reactivation can be carried out by placing the silica gel in a fan-forced oven at 110°C for 5 hours. The beads will return to their original colour as they are reactivated.
This process can be repeated up to three times, after which effectiveness may begin to decline. Always follow the reactivation instructions for the particular silica gel product you are using.
How Much Silica Gel Do I Need?
Choosing the correct amount of silica gel is important for effective moisture control. Pro-Ex offers silica gel sachets in a range of sizes, including: 0.5g | 1g | 2g | 5g | 10g | 50g | 100g | 500g
Continuous roll and indicating silica gel options are also available.
As a general guide, Pro-Ex recommends approximately 5g of silica gel per 1 litre of air volume. However, the appropriate amount can vary depending on the particular application.
Not Sure How Much Silica Gel You Need?
Rather than guessing, use the Pro-Ex Silica Gel Calculator to help determine the appropriate amount for your application.
Alternatively, contact the Pro-Ex team for assistance selecting a silica gel product to suit your packaging, storage conditions and moisture protection requirements.