What is a dry cabinet?
A dry cabinet, also called dehumidifying cabinet or dry box, is a storage solution used to protect sensitive items from excess humidity. These devices are used across many industries, but they are particularly popular for sensitive camera equipment storage. The main issue dry cabinets serve to fight is fungal growth. Cameras and camera lenses are susceptible to fungus given the right conditions – darkness and excess humidity.
Dry cabinets come in various shapes and sizes and there are different technollogies available. As opposed to it’s name, a dry cabinet’s purpose is not to provide an environment devoid of any humidiy, as this might actually be detrimental to the equipment encased within. Much like a cigar humidor, the dry cabinet’s job is to maintain an optimal relative humidity. Most dry boxes are equipped with a hygrometer to allow you to check the humidity level inside.
How does a dry cabinet work?
Dry boxes can be broadly divided into two categories: active and passive. A passive model utilizes a dessicant inside an airtight sealed box, and typically offers limited control over the humidity level. These boxes require no electricity to operate, but need regular dessicant changes (or reactivation for multiple-use dessicant), especially when activelly used. Therefore, a passive dry box is a good solution when power consumption is an issue, for example in an off-the-grid application. For regular home use, an active dry cabinet is generally a simpler and more effective solution.
The typical active dehumidifying cabinet is an enclosure with electronic humidity control that automatically maintains a stable relative humidity (RH) at a preset level. Simpler models usually feature a small Peltier element to condense and remove the air-bourne moisture. More advanced models operate using multi-porous molecular sieve desiccants with automatic regeneration mechanisms. Electronic dry boxes are much more precise and reliable than passive models, but do require a constant power source.
Do you need a dry cabinet?
Whether or not you need a dry cabinet depends on your location, climate, gear and use patterns. Climate is generall the number one factor determining the need of such a device. If you live in a warm, humid climate like Southeast Asia or equatorial states, chances are a dehumidifying cabinet would be a wise purchase. Even the cooler temperate climate can provide enough moisture to cause trouble in the right conditions, especially in seaside areas.
Usage patterns are the second most important factor when you consider a dry cabinet for your equipment. If you constantly use your gear, day in and day out, the chances of it developing moisture related issues is minimal even in a moderately humid climate. Having the cameras out in the open, in sunlight and air, would usually suffice to prevent fungal growth in all but the most extreme cases.
On the other hand, if you find yourself storing your equipment for several months at a time, you might find a nasty surprise under a lens cap one day. The risk of fungus issues increases if you often work in wet, dewey conditions. In a humid environment, gear will accumulate moisture even if kept out of the rain. Putting away equipment in a dark, warm cabinet after such a shoot is a great way to grow some fungi.
How to use a dry cabinet for camera storage?
Using a dry cabinet for camera storage is a straighforward process. The amount of work you have to do depends on the type of enclosure you are using. With an active dry box, the only thing you need to do is to set the desired humidity level and let the electronics do their work. Best humidiy level for camera storage is around 40-45%. If you are using a passive dry box, you need to add enough dessicant to keep the humidity close to these numbers.
Too dry can be almost as bad as too humid, which is why using a dry box without means of determining the actual relative humidity inside is a bad idea. Storing your gear in an enclosure with extremely low humidity will affect rubber parts, leatherette, certain plastics, lubricants and some electronic components. Electrostatic build up is also a danger when humidity is kept too low.
Storing your gear in a dry box is no different than storing it in a regular cabinet. Make sure cameras and lenses are clean and surfaces are dry. Coming into a heated house from a cold exterior may lead to condensation. It’s best to give your gear time to match the ambient temperature while it’s still sealed inside bag or case, and only put it in the dry box once it’s fully acclimatized. Fabric straps can soak up moisture, so if yours can be easily detached, it can be a good idea to remove it before stowing away the camera.
Every time you open the door of the dry cabinet, humid ambient air will get inside. In an active dry box, this means that the dehumidifying mechanism has to work extra hard removing the newly present moisture. With a passive box, prolonged open periods will quickly saturate the dessicant, rendering it useless. As with a fridge, keeping the door of the dry cabinet open for the shortest possible time is benefitial.
Can a dry box kill fungus?
As fungus requires moisture to grow, a dry box can prevent fungus from growing. However, it does not kill nor remove fungus from a lens. Keeping a infested lens in a dry cabinet will retard fungus development but it will not clear any growth out. Fungal spores are pretty tough, and in the absence of moisture they go into hybernation. The only sure fire way of getting rid of fungus is mechanical cleaning and UV treatment.
If you suspect a lens has been exposed to fungi spores, (for example if another lens of the same set has visible fungus) keeping it in a dry cabinet after a thorough cleaning is a good idea. This will eliminate the risk of the lens developing fungal growth while in storage. However, just keeping a lens in a dry box will not remove any potential spores. Should the right conditions present down the road, the spores will reactivate and start growing.
Storing film in a dry cabinet
Processed film storage is another area where a dry box may come handy. While packaged, unprocessed film is pretty much air-sealed and cares little for ambience humidity, it is not so for developed negatives or slides. Properly processed black and white negatives can last almost indefinitely, but they do need to be kept in the right conditions.
Storing your camera equipment and negatives in the same cabinet may seem convenient but it’s not ideal. Optimal relative humidity for processed film storage is around 30-35%, which is a bit too dry for cameras and lenses. In addition, film prefers temperatures below 10°C (50°F) for long-term storage, which may not be practical for equipment that is used daily. Film also does not like fluctuations in humidity and temperature, which will also arise every time you open the dry cabinet to access your gear.
Therefore, if your climate requires processed film to be stored in a dry cabinet, it’s best to provide it with one of it’s own.
What are dry cabinet alternatives?
Hard Case + Dessicant
Keeping your gear in an airtight hard case with some dessicant thrown in is a popular alternative to a dry cabinet. Hard cases come in all different shapes and sizes and are perfect for a DIY dry cabinet setup. The Peli 1510 is a popular option, since it’s right at the maximum size for carry-on luggage and fits a fair amount of gear.
This setup comes with all the specifics of a passive dry box, with the added benefit of providing gear protection while being easily transportable. To avoid some of the caveats of dessicant humidity control, it’s best to equip your case with a hygrometer.
DIY Dry Box
A homebrew dehumidifying cabinet is a popular DIY project for photographers. There are many different designs and approaches out there. If you go for a passive design, this usually involves dessicant in an airtight enclosure such as a plastic storage container or storage cabinet.
Active options range from simple heat-based models to more sophisticated Peltier based projects. Whichever way you decide to go, keep safe and get a hygrometer to manage humidiy properly.