Why sealed CCTV cameras still fog
Lens fogging occurs when the internal temperature of the camera drops below the dew point of the air trapped inside the housing. When this happens, moisture condenses on the coldest surfaces, typically the inner face of the lens or dome.
This often appears:
- At dusk or during rapid night-time cooling
- In spring and autumn rather than mid-winter
- After rainfall followed by clear skies
- Even in cameras that have never leaked
Crucially, the moisture causing fogging is already inside the enclosure. It may have been trapped during manufacture, installation, or drawn in during pressure equalisation as temperatures cycle.
A camera can be perfectly sealed and still fog repeatedly.
Why heaters are an incomplete solution
Many CCTV housings rely on small internal heaters, but these have limits. For example, they only work when powered and they also increase energy consumption. Importantly, they can create thermal gradients that drive moisture migration. Not only does this not remove moisture it also masks the symptom by postponing condensation.
In cold climates, heaters can help, but they do not address the root cause; that of excess water vapour inside the enclosure. Under marginal conditions, heaters may push moisture to the lens, where it condenses once heating stops.
Why desiccant often fails in the field
Silica gel sachets are widely used, but in CCTV cameras but users often report they worked for a few months, then the fog comes back. The reason is there is little room for enough Silica gel, and once it saturates, there is no regeneration capability, and it is not easy to replace.
A better approach: humidity stabilisation
For sealed CCTV housings, the objective is not to create ultra-dry air.
What matters is keeping internal relative humidity below the condensation threshold across temperature changes.
In practice, this means:
- Absorbing excess water vapour when relative humidity (RH) rises
- Releasing it gradually when conditions improve
- Preventing rapid RH spikes that lead to dew formation
Known as humidity buffering, it is widely used in optical, telecom, and outdoor control enclosures with restricted servicing access.
Why Drykeeper is well suited to sealed CCTV cameras
Drykeeper is designed specifically for small, sealed, maintenance-free enclosures — exactly the environment found in CCTV housings.
Instead of relying on heaters or consumable desiccants, Drykeeper:
- Passively stabilises internal humidity
- Operates without a power supply
- Requires no servicing or replacement
- Continues working across daily temperature cycles
- Has a service life measured in years, not months
By keeping relative humidity in a safe mid-range, Drykeeper prevents the conditions that cause condensation to form in the first place, even during rapid cooling at night.
Typical CCTV applications
Drykeeper is particularly effective in:
- Fully sealed outdoor CCTV cameras
- Dome cameras with internal condensation issues
- Roadside and traffic monitoring systems
- Perimeter and security cameras in remote locations
- Installations where heaters are undesirable or impractical
It is especially valuable where maintenance access is difficult or costly, such as poles, gantries, rooftops, or infrastructure sites.
Reduced callouts, clearer images, longer service life
From an installer’s perspective, lens fogging is more than a nuisance. It leads to:
- Customer complaints
- Missed evidence
- Return visits and warranty discussions
- Reputational damage
Addressing humidity at the root cause, rather than reacting to fogging after it appears significantly improves long-term system reliability.
Learn more
If you are specifying or installing sealed CCTV cameras and are experiencing intermittent fogging or condensation, passive humidity control may be the missing piece.
➡️ Learn more about Drykeeper and how it works in sealed enclosures at Passive 10-Year Humidity Control for Outdoor Enclosures – Rosahl
➡️Understand the science behind Drykeeper at Introduction to Drykeeper for controlling enclosure condensation
Evaluation
Drykeeper is sold in pack quantities for commercial and industrial projects. Individual sheets are not sold separately and the sheet prices shown are for reference only.
If you have a commercial project and would like to discuss samples and prices, please use the contact us form,