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July 1997 Vol. 23, No. 7   RSS Feed for Undercurrent Issues
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Attack of the Salt Demons

Rituals for the care and feeding of O-rings

from the July, 1997 issue of Undercurrent   Subscribe Now

Do evil spirits cause flooded cameras? A lot of us laugh at such an idea, then continue with our personal preventive maintenance ritual. After all, if it works, it must be right.

Care and treatment of Orings, especially concerning the effects of salt buildup, is, for many, 50 percent care and 50 percent ritual. One diver checks and cleans the camera's O-rings after every dive, another every evening, and a third only at the end of the trip. All appear to get good results, so each diver thinks that he or she is doing the best preventive maintenance.

Understanding the internal O-rings of a camera (or, for that matter, camera housing, strobe, underwater light, computer, hand-held sonar -- any electronic device with changeable batteries) and the silent damage done to them by salt crystals offers some hope of reducing dependence on ritual. The questions: (1) How do salt crystals affect O-rings and the grooves in which they lodge? (2) How many immersions does it take for salt crystals to harm them? (3) How does one prevent this harm?

In the course of 30 years of shooting underwater pictures, I've collected lots of stuff. I've dunked Nikonos cameras, Ikelite, Aquatica, Tussey, Oceanic, Sony, and Quest housings, plus associated strobes and lights, and the only floods I remember are those resulting from dumb foul-ups. Like the student whose husband made her so nervous that she forgot to bayonet a 35 mm lens into the Nikonos. Or the time my attention wandered and I forgot to replace the O-ring in a Subsea 150 strobe.

Does this mean that floods occur only because of dumb mistakes? If not, how does one keep camera seals from letting water in?

Salt Crystals = Sharp Teeth

O-rings are the rubbery gaskets that seal openings of underwater equipment to keep water from entering under pressure. They are made from two kinds of materials. One is the good old black butyl rubber, the kind used in O-rings on most units a sports diver is likely to have. The other is the red or blue silicone of O-rings found on a few other devices, such as the Nikonos RS and certain Sea & Sea products. (Silicone rubber is said to withstand more squeezing, and thus greater pressure, than butyl rubber. It also remains more flexible under conditions that make butyl rubber stiff and rigid.)

Silicone or butyl, O-rings aren't immune from salt buildup, unless you do all your shooting in fresh water. Salt cakes on the rubbery material, much as grains of salt in a salt shaker clump together in humid weather. (Information for techies: when salt water evaporates, the salt remains -- a process called crystallization, in which ions of sodium and chlorine arrange themselves in a definite geometric relationship with each other.) The buildup is sneaky, hardly noticeable over a week's worth of diving immersions. But just as grains in a salt shaker can remain loose for a day or two in humid weather, then become unshakeable, the salt monster eventually catches up with O-rings. As the crystals grow, pressure forces them against the camera's seals, slowly cutting into them.

Result? Well, nothing, at first. Because the buildup process is slow, effects of salt buildup aren't dramatic -- until that awful moment when you open your camera to find a tiny swimming pool inside. As salt buildup slowly cuts into the Orings, their surfaces begin to roughen with tiny cracks. They lose flexibility and they don't fill the camera or houseing openings they were designed to fill. Salt buildup also does a job on metal sealing surfaces. Over time, tiny pits form in the grooves. Eventually, pressure can't force the O-ring into the irregular extra spaces, especially at shallow depths.

On O-rings that you can get at -- providing you take care of them -- this crystallizing process doesn't get far. It's the internal ones, the ones you have to void the warranty to remove, that usually end up causing trouble. The rewind knob on the Nikonos V, for example, sports three hidden O-rings that accommodate the vertical and rotary actions of the shaft and ASA/ISO dial.

Servicing user-replaceable O-rings depends on rituals of greasing and watering that will keep you in your cabin every evening. The effectiveness with which these O-rings are cleaned and lubricated and the thoroughness with which the camera is rinsed help determine whether or not your camera keeps salt water outside.

Apres-Dive Habits

After each dive, and before doing anything else, submerge your camera in fresh water. Any dive boat or diving resort worth its salt has one, and the better ones offer a special rinse tank for cameras. If your destination is so rustic that it doesn't have a rinse tank, you may wish to invest in a Wet Bag (603-432- 1997), special luggage that doubles as a water container.

Unless your camera is part of a large rig, don't remove any accessories. (Big housings or systems with multiple strobes may not fit well in the rinse tank. Detach the major components, but don't disconnect any electrical connections.) With lens caps in place, swish the camera up and down in the rinse tank several times to force fresh water in and out of the camera's nooks and crannies. Leave the camera in the rinse bucket for at least a few minutes (but take it out before that diver with the giant video rig gets impatient and drops it in on top of yours).

You may want to change film, videotape, or batteries before your next dive, and you'll need to perform a basic cleaning job when you open the camera. First, make sure the camera is dry, and change the film or other items before doing any cleaning. Then remove the main O-ring (if it isn't fastened in place) and lay it aside. Carefully clean the mating surfaces that compress the O-ring. One or two clean cotton swabs or a piece of well-washed cotton fabric will do nicely. [Ed. note: For another opinion on cotton swabs, see one reader's rant in the June issue.]

Next, slather your thumb and forefinger with a bit of the lubricant that is appropriate for the material your O-rings are made of (don't use silicone grease on a silicone O-ring). Run the O-ring through your greasy fingers, rubbing thumb and forefinger together to feel for tiny pieces of grit. Rid your fingers of dirt and excess grease by wiping them on a paper towel, your pants, or some other material you don't mind getting dirty. Again run the O-ring between your fingers to make sure it's slippery but not dirty. Carefully reassemble your system.

After Your Final Dive

You've got things to do at the end of the day. At the very least, take a cool (not hot) shower. Not only will it be good for you, but your shipmates will appreciate it. Most important, take your camera gear into the shower with you and let it rinse as long as you can. (On a dive boat and at many dive resorts, fresh water may be at a premium. Check with the management. This is another good reason to bring along a Wet Bag.)

Next, do the same cleaning job you performed after each dive. This time, remove, check, clean, and replace all userreplaceable O-rings.

After you've finished this ritual, rejoin your diving companions, if they haven't already turned in.

The Final Recipe

These last steps probably are the most important you perform to rid your equipment of salt crystals. Sure, they're a bother, but isn't this why you wanted to get into underwater photography in the first place?

Don't unpack your dive or camera gear when you arrive home -- at least, not until you get near either a laundry tub, a bathtub, or (weather permitting) at least one large, clean plastic barrel outdoors.

Fill whatever container you use with fresh water. (Note: keep your salty exposure suit out. It may look great and keep you warm, but it doesn't rust and it isn't filled with electronics.) Special chemicals are available. One is a called Salt-Away (800- 221-0889). I haven't used it, but I hear it helps reduce corrosion on dive and photo equipment. A small quantity of plain vinegar (the hardware-store, not food, variety) also may help. Because the acid in vinegar can etch glass lenses, we're talking capfuls here, not whole bottles.

Check that your equipment is sealed, then swish each item in the water as you did during the trip. Empty and refill the container at least once more. Then let everything soak for at least 24 hours; a week is even better (but not with chemicals such as vinegar).

Operate every control repeatedly. For example, work the shutter release and cocking lever on your Nikonos about 40 times, go away, then come back a few hours later and do it again. Turn the camera's ASA/ISO dial back and forth, but don't raise the shaft of the Nikonos V's rewind crank. Read the instructions that were packed with your equipment.

Finally, dry everything. Use towels to pat-dry lenses. A hair drier set at low heat helps remove water from hard-to-reach spots. Remove water spots from lenses.

Some underwater photographers suggest removing userreplaceable O-rings before storing the equipment. Because I'm afraid of forgetting to replace the O-rings, I don't store them separately; as far as I can tell, no ill effects have resulted. If you pull the O-rings, pack them in zipper-type plastic bags and attach each bag to its applicable equipment.

Use It or Lose It

The best way to keep the salt dragon at bay is to keep using your gadget. Your camera (or strobe, housing, whatever) wasn't designed to sit on a shelf. Providing you treat it carefully, operating the gears and levers and soaking it in the ocean is what you're supposed to do with it.

So what will it be? Will you placate the flooded-camera gods after each dive, each day, or after the trip is over? My recommendation is to perform all three rituals. You can never be too careful.

And if all that isn't safe enough, send your delicate equipment to its manufacturer or a repair service at least once a year. Repair services tell me that many cameras they check have received little if any care. Maybe that's why they're so popular.

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