The myth of the camera rinse tank
In today’s age, most dive boats or shops will have a camera rinse tank. You’ve likely heard in one of your dive briefings that the camera rinse tank is only to be used by cameras. This statement is usually followed up with some line about how you should never put your mask in the camera bucket, as the mask defog will affect the the camera seals in some horrible and catastrophic way.
I’ve heard this for many years. But is it accurate? Like any myth, there is likely to be a kernel of truth that has become distorted over the years as it’s passed from one divemaster to the next. So let's examine this more closely and find out.
We begin by looking at the camera o-rings. Almost 40 different types of rubber compounds exist on the market today for o-ring use. O-rings used in underwater photography are generally one of the following:
Nitrile, sometimes called Buna
EP, or EPDM
FKM, or Viton,
Next we can ask, what are the compounds we might find inside a mask rinse bucket? Aside from the obvious - water, we can assume that one could find trace amounts of mask defog products, including the commercially made ones as well as the home made versions using shampoos or soaps. We also could conceivably find other products like:
Bleach - this is not unheard of and sometimes trace amounts of bleach will be put into a rinse bucket for cleaning purposes or to mitigate growth of mold.
Vinegar is commonly found on a dive boat to treat stings, and it is possible that some of it can find its way into the rinse tank.
Sunscreen - trace amounts of sunscreen could easily be in a rinse bucket, from the hands of divers going in and out of it.
Lastly we examine, can any of these chemicals or products adversely affect the o-rings in the underwater camera housing?
When we look up the material specifications for the four o-ring materials listed above, we quickly see that all of them have very good chemical resistance. The exception to this is when these materials are exposed to certain solvents. We will set aside the fact that solvents should never ever be found inside a rinse bucket, however since these chemicals could be found in a dive boat compartment somewhere, we will consider some of them as well.
So how do we determine what product affects what o-ring? We took samples of all 4 types of o-rings, Buna, EPDM, silicone, and Viton, and submerged them in a variety of different compounds. In addition we had a control sample that was simply sitting in air. The compounds were:
500 PSI defog
McNett Sea Drops
Jaws Quick Spit Antifog Spray
Tide laundry detergent
Johnson & Johnson baby shampoo
Tropicana sun screen
H7 degreaser - Very commonly found on dive boats.
Deoxit Gold contact cleaner - Used commonly to clean electrical contacts.
Goo Gone degreaser - Used commonly to remove decal glue.
Boeing T9 protective spray - This is commonly used in marine applications to protect metal parts from saltwater corrosion.
Brake Cleaner - It is in some dive boat compartments - used in cleaning.
Rain-X - I have heard of some photographers coating their dome ports with this, to help water sheer off better when doing over/under shots.
In a few cases we cut the o-rings into smaller pieces as we had a limited sample of the silicone o-rings on hand. Each o-ring set was cleaned with Dawn dish soap and dried. The control sample was isolated in a separate location. They were then placed in their respective container and left to sit for a period of 48 hours.
After 48 hours we removed, cleaned again with Dawn dish soap, dried and examined them. Lacking proper testing equipment, we had to find ways to measure if any changes had occurred to the o-ring.
Feel. Each o-ring was removed, cleaned and dried and examined by touch to see if any physical changes could be felt (such as difference in texture.) Admittedly this is a very subjective test, but we wanted to see if any obvious differences had occurred.
Size - each o-ring sample was measured 3 times with digital calipers, averaged, and compared to its control.
Examination under magnification. Each o-ring was examined under high magnification for any signs of changes.
The amount of words we type in our blog is a delicate balance between the amount of information we wish to convey and how much we want to bore the reader. In lieu of a spreadsheet full of numbers, I will summarize here. For those who wish to see the full data, kindly email me.
For samples 1-8, that is products we might find in trace amounts inside a rinse bucket, we found no difference between the control o-ring, and the samples we tested. They were identical in appearance, texture, and size.
For samples 9-14, products we should not find in a rinse bucket, we did make a few surprising observations:
For the brake cleaner, I really expected this to deteriorate some of the o-rings. However on inspection, all of them were identical to the control sample. That said, the brake cleaner almost completely evaporated after 48 hours.
For the Goo Gone and the Rain-X, I was very surprised. At first glance you could see that the silicone o-ring samples had appeared to double in size. After several measurements, it was determined to be actually 30% bigger - 2.75 mm average measurement, compared to 2.1 mm of the control o-ring. The viton and buna o-rings had no change at all.
This experiment, while not as scientifically controlled as we would have liked, serves as a useful guide. Remember this is an extreme test, in that each o-ring was subjected to 100% exposure of the chemical or product in question, and not trace amounts as one would expect to find in a rinse tank. Furthermore the duration of the exposure was far longer than one would normally have in a rinse tank.
I feel it’s reasonable to conclude that products one would normally find in a mask rinse bucket - products like scuba defog, soaps, or shampoos would have no adverse effect on the o-ring seals of an underwater camera housing.
There are certainly chemicals out there that can and will affect a housing o-ring. However if these are found in enough concentrations to cause damage to an o-ring, the dive shop has much bigger problems - these chemicals in that high of a concentration would certainly not be safe to be near your eyes or on your skin.
Back to the myth
So where did this myth come from? It’s hard to say with any certainty, but here are my suspicions:
From 2009 - 2012, I worked as the Service Manager for a Reef Photo & Video. I was the guy that managed and assigned service orders to my technicians, made estimates, and gave bad news. A large number of my estimates were for flooded camera and housing repairs. The first thing I can tell you is, the camera rinse bucket is a bad place, contents of the water notwithstanding. I kept statistics on camera floods, and while I no longer have access to them, I can tell you from memory that the vast majority were from when a camera was left unattended in the rinse tank.
Camera housings are designed to withstand water pressure. The deeper we go, the more pressure on the seals and the tighter they become. Underwater at depth, even if you wanted to pull your dome port off the housing, there’s no way you’d be able to due to the water pressure. On a 6-inch dome port at 33 feet, there is about 416 pounds of pressure squeezing that port onto the housing.
But in a camera rinse tank it’s different. The camera is surrounded by water, but under minimal pressure - often just a foot or two. In a foot of water, the pressure on the dome port has been reduced to just a few pounds. A good bump or movement can easily dislodge this amount of pressure, and this is where most floods occur.
The other issue is that cameras sometimes do not sit in the rinse bucket alone. Depending on the boat and the manifest, you could potentially find your camera at the bottom of a large pile - a pile that is being tossed around with the motion of the ocean. Some underwater housing designs have better port interface designs than others. There are a few designs on the market that can be highly susceptible to leaks in the port caused by impact at low pressure.
When a flooded camera is pulled from a rinse tank, it’s a traumatic experience. The customer will go through the 5 stages of grief, albeit perhaps in a much quicker manor, and they always want an answer to the question “why did this flood?"
When there is no clear explanation, human nature causes us to assign some sort of blame. The old - “I saw someone rinse their mask in there,” will raise its ugly head. Humans don’t like unsolved mysteries, and we tend to look for cause and effect, even if it’s not the correct answer. At face value, this can be a logical argument that is easy to accept. I left my camera alone in the rinse tank. It flooded, therefore something in the rinse tank must have caused this.
Over many years, divemasters hearing the agonizing wails of photographers pulling flooded camera systems from the rinse bucket may have led to a simple and outright rule - no masks in the camera bucket. After all, if only the photographer goes in the camera bucket, it can’t be anyone else’s fault. With camera systems running in the tens of thousands dollars, it’s an argument no $7 per hour divemaster wants to be in the middle of. Nor do the dive shop owners, who will be occasionally asked to reimburse the customer for their multi-thousand dollar loss.
The following illustrations give a representation of how a lack of pressure can affect an o-ring seal. Please remember that each housing design is different, and some have different styles of seals. This is merely an example.
After reading all of this you’ll probably be disappointed to learn that my advice is to change nothing in what you are doing. I do think it’s a good practice to avoid the camera rinse tub if you can. Don’t put masks in there, simply because there will be a potential for you to bump someone’s camera. If a photographer with a $12,000 setup does pull it flooded from the bucket, you don’t want to be on the accusation list, even if it is completely unfounded.
For photographers, avoid the rinse bucket! (Are you detecting a theme here?) It's fine for rinsing, but don't leave them soaking in it. I’ve personally found that the best method is to carry your camera gear around in a large soft-sided cooler. These are large enough to fit the entire setup, they are waterproof, and they are padded. After my dive, I dunk the housing and strobes in the rinse tank but I don’t leave it there. Then I move it to my camera bag.
Thanks for reading! Any questions, please feel free to contact me through this page. Hope to see you diving with us soon!