Peter Rowlands Seal test Snorkel test

To many divers, a mask is simply one of those pieces of equipment you don't have to worry about - a combination of face seal and glass, incorporating nose access for ear clearing. In a way they are quite right, but as with all simple things, you have to choose the one that's right for you. Choose the wrong mask for your face and you won't enjoy your diving - it's as simple as that.

Unlike regulators, which can be tested and compared for performance, masks are more personal and form-fitting - so the ideal mask for, say, my face profile and usage would probably not suit you (unless you are squat-faced, short-sighted and like to look through a viewfinder for most of the dive).

Masks have been around longer than the aqualung, and their design has evolved radically since the days of the infamous 'ping pong' snorkel. Today, some divers say that the only changes in mask design are the contours and colours of the fashion parade. Not so - just as diving has its specialities, so masks have evolved to suit different needs.

Accordingly, DIVE decided to look at masks in general and see how their designs are dictated by and suit their various purposes underwater. In addition, there is a lot more to mask preparation, use and storage than is usually discussed, so we'll cover everything from choosing the right one, initial cleaning, safe transportation, pre-dive preparation, underwater performance and post-dive care.

The performance of your mask during a dive is, assuming a smooth supply of air, the most important aspect for a comfortable dive. Choose the right mask for your needs and it will provide you with clear, safe vision.

For those to whom style is the most important consideration, I would urge you to make this the last consideration… and bear in mind that black goes with everything!

SECTION ONE
CHOOSING YOUR IDEAL MASK

THE SEAL TEST

First and foremost, the mask must complement the profile of your face and provide a simple water seal without forcing you to overtighten the strap. In fact, the best way to test a face seal is without the strap in place. Simply place the mask over your face with your hair swept back, then breathe in slightly through your nose. 'Slightly' is important here, because any but the worst-fitting mask will provide a seal if you breathe in enough to make your eyes bulge. Having breathed in slightly, a good mask seal will hold it in place when you take your hand away. Anything less and it will quickly fall away. If this happens, look for a different shape of mask.

As any diver can attest, there are a lot of different faces out there! Still, the majority of faces can be accommodated in a good mask. There are sizes for those with thinner faces (such as women) and smaller ones for children, so finding the right size is simply a question of shopping around. Take time to decide on the best mask for you and, if necessary, visit several shops to try different ranges.

If you plan to use a snorkel it is important to try this at the same time, as your face profile can change with the mouthpiece in place. A word about facial hair and mask seals - everyone will tell you that hair disrupts the seal, but when I was the proud owner of a moustache, it did not lead to the mask flooding.

DESIGN OPTIONS

While the seal is by far the most important in terms of comfort and safety, your intended use for the mask will dictate the best design for you - this is where the glass port and skirt designs come into their own. Glass ports are usually single or dual pane - singles give you an unencumbered view, but their design has to place the glass further from your eye so your left-to-right vision will be reduced. Dual-pane designs allow the ports to be much nearer your eyes, which improves left-to-right vision considerably. You would have thought that the interocular gap between the panes would cause a 'binocular' effect but in practice it is so close that it becomes invisible.

It is fair to say that the majority of modern masks are of a dual-pane design, but there are some which incorporate more by adding 'windows' at each side (and even some with down panes) to help peripheral vision. While this does afford some additional vision, the result is quite prismatic (with light entering the mask at different angles) and can vary with head and light angles. A recent improvement on this design uses the opacity of the clear silicone skirt to aid peripheral vision (see mask below). It produces no prismatic effect and the view is obviously slightly diffused, but it's surprisingly handy at spotting peripheral movement. Obviously, the black skirts favoured by photographers, technical divers and spearfishers preclude this benefit!

CORRECTIVE LENSES AND MASKS

For most of us, advancing years brings the problem of long-sightedness and the need for either longer arms or dioptre lenses to make gauges and computers readable. The latter are certainly more practical, and come in four forms - stick-on or bonded in semi-circles, whole-pane optics or specialist variofocals.

The whole pane optics are more suited to those with short-sightedness where a minus (-) dioptre of suitable strength will bring infinity back into focus. For those who need reading glasses (long sighted), plus (+) dioptres are needed but whole pane option would make distant subjects unsharp so a better solution is stick on semi-circles as with bifocals on land (see above). The bespoke solution is to have specialist variofocal lenses made, but these are much more expensive and should be protected in a very rigid box.

I always carry my mask in hand luggage ever since my dive bag got lost on one trip. I was able to hire everything else except my prescription mask. Anyone who dives with a prescription mask should carry a spare.

FULL-FACE/COMMS MASKS

These are for more industrial uses, where divers need to talk to their surface cover/controller. They come in various forms, from a simple full-face mask with regulator orifice right up to the OceanReef/Kirby Morgan commercial diving masks.

These masks (see below) are bigger and heavier than conventional masks and require special training prior to use. One side-effect of wearing full-face masks is that users seem to get through more breathing gas, possibly because they can be so comfortable that you breathe more fully simply for the pleasure of it!

SECTION TWO
IF THE MASK FITS...

SNORKELLERS AND GENERAL DIVERS

Snorkellers or generalist divers should choose a mask with a clear silicone skirt (see right), which serves to increase light levels, at the same time reducing the claustrophobic effect. Pane design is a personal preference, with a choice between the unencumbered view of a single pane and the low volume and wider view of the dual pane design. A quick look at masks for this market will confirm that the most popular ones are dual pane with clear silicone skirts.

COLD-WATER DIVERS

A lot of serious cold-water/professional divers use full-face masks (see left) to help keep warm. If diving with a conventional mask, a larger hood is recommended to cover the mask skirt and forehead area. American divers in Antarctica use regular masks, but favour a balaclava-style hood - with only a tiny hole to accommodate the mouthpiece - for maximum insulation.

UNDERWATER PHOTOGRAPHERS

whether they shoot stills or video, these divers tend to opt for low-volume dual panes with a black silicone skirt (see left). This cuts out any extraneous light and provides the diver with a more contrasty image to view either the subject matter or the camera's viewfinder.

FREE-DIVERS

The most important feature of a competitive free-diving mask is its internal volume. The smaller the volume, the less air is needed to equalise, and when you've only got one lungful, low-volume masks are vital. Black skirts are also favoured as a means of limiting visual distractions.

SECTION THREE
KNOW YOUR MASK

PREPARING A NEW DIVING MASK: The skirt on most modern masks is made from silicone. During the manufacturing process, silicone residue rubs off on the inside of the mask's glass surface. This film must be removed before diving. If you leave it as it is, the mask will comprehensively fog, no matter what defog solution is added to the inside of the mask. There are commercially produced solutions (such as Sea Buff from McNett) for cleaning new masks, but an old favourite is simple toothpaste, which provides sufficient abrasion without the risk of scratching. A small drop on the inside of each pane (see below) rubbed several times across the whole surface area should clean the surface perfectly, and it does no harm to repeat the exercise on the outer panes.

BEFORE YOU DIVE: There are commercial products such as Sea Drops from McNett, which stop masks fogging up during a dive. A couple of drops on each inner surface (see below), gently rubbed over the whole area will suffice and this should be rinsed in either fresh or salt water before it dries. The popular solution is cheaper, much more readily available and comes in the form of your own spit. Rather like Sea Drops, only a small amount is needed and there is definitely no improvement even if you empty the entire contents of your nasal passage. Sometimes less is more. During the dive, try to avoid exhaling through your nose as this may cause fogging to reform. In addition, any water entering your mask and getting onto the inner glass surface could encourage fogging.

STRAPS AND ADJUSTMENT: Straps are invariably made of the same material as the skirt, which is usually silicone. They should be strong but stretchy, and provide good support. Most designs incorporate a one-way ratchet (see right), which the wearer pulls to tighten, but you need to push a catch to release. In practice, once you have made this adjustment, you should only need to readjust it if your hood thickness changes. It is advisable to carry a spare strap as they can break at the most inopportune time.

The standard straps are quite 'clingy' when slipping over a neoprene hood and especially so over hair (dry hair being the worst). Many people choose to replace the standard strap with a neoprene-backed one (see right) which spreads the load over a wider area and is easier to slip on.

Divers should be aware that some post-dive headaches are attributable to straps which have been tightened with too much force. Experiment with the tightness until you identify the point at which little or no water will enter your mask - you don't need to tighten much beyond this point.

POST-DIVE AND TRANSPORTATION: A simple rinse in fresh water will be sufficient for routine maintenance. The tempered glass is uncoated, so any droplets which dry will not leave a residue. However any masks with tints, coatings or optical dioptres should ideally be dried with a soft cloth or tissue.

Your mask is at risk when being transported to and from the dive site. Most new masks come with rigid see-through boxes for protection (see above) and these are fine for most purposes. As I have reading lenses in my masks, I prefer the extra rigidity of a small Pelican or Underwater Kinetics case.

SECTION FOUR
DIVERS AND THEIR MASKS

DAVID DOUBILET
UNDERWATER STILLS PHOTOGRAPHER

'There must be at least a thousand different species of masks that appear on the market across the globe. Still, I have not managed to find one that is designed for the nasally challenged diver. I find this rather remarkable given that one of the fathers of scuba, Jacques Cousteau himself, had an imperial-sized beak.

I wear a not-so-chic Nemrod Bali oval mask for two simple reasons. It fits and it's comfortable. The black rubber skirt cuts down on unwanted ambient light and focuses my attention to viewfinder, while the giant oval window accommodates ever-changing prescriptions - now including bifocals. The Nemrod company ceased to exist a decade ago and I now cautiously guard a diminishing stockpile of new masks still in their boxes like a miser counting gold!'

PETER SCOONES
UNDERWATER CAMERAMAN

'For many years I have used low-volume masks - the smaller the better. They all came in black silicone, which is so important when peering into viewfinders. A bonus with some of the low-volume types is the ease with which you can obtain corrected lenses. For some time I was using Mares masks, several models of which took interchangeable corrector lenses. The shape of the lenses meant that each side was symmetrical, so lenses could be swapped over. I should explain, I'm short-sighted, I have been in the habit of using one eye corrected the other not, with plain glass on that side. This meant I had both distance and close-range vision. Changing the lenses over gave each eye exercise. Then the mask design changed and the right and left were not interchangeable any more. When I met Eddi Fromenwiler in the Banda Sea and tried his small bifocal corrected mask, I had to have one. Pingel Optik of Düsseldorf supply masks fitted with the bifocal lenses. Since I've been using these masks I've had no need to look further.'

MARTIN STEPANEK
COMPETITIVE FREE-DIVER

'For free-divers, the most important consideration when choosing a mask is the inner volume. The mask needs to be equalised during descent and each equalisation means a loss of our precious air. Who has the smallest mask with the best field of vision? An Italian company called Technisub has solved this question for me with a mask called Sphera. There is no mask on today's market that has a smaller volume than this one. Its frame is also made out of very flexible plastic. So when I go for the ultimate depth and my lungs get compressed to the point that there is no more air in them that I can use for equalisation, the mask simply moulds onto my face without causing any damage.

ANDY CLARK
POLICE DIVER

'Widely employed by police dive teams around the country, the Divator MKII is a reliable and trusted open-circuit positive-pressure mask which copes more than adequately with the demands placed upon it. The rubber mask incorporates a low-volume flat visor and is fitted via the tightening of a spider strap. The soft rubber inner mask moulds to the shape of your face and, combined with the positive pressure within (0.3-bar above ambient), ensures a perfect fit.

Technicalities aside, the Divator MKII is a lovely bit of kit! It provides a warm, dry, comfortable dive and I have great confidence in its ability to act as a barrier against both the cold and any pollutants in the water.