The scuba mask has one small job, create and maintain an air pocket in front of the eyes. Still, a leaking mask is the most often occurring equipment issue leading to a unsatisfying dive. It is also a leading trigger event that leads to an accident. A scuba mask is one of the first items of gear you should buy. Peoples faces have different characteristics and while a certain model of a mask may fit a wide range of facial features, none will fit everyone. Also, rental mask are likely the most abused piece of equipment a new diver will encounter, and in turn abuse themselves mostly due to lack of knowledge. While sturdy, they need to be treated gently and protected from damage. For these reasons, most dive instructors will recommend buying a mask as soon as practical. Most dive instructors and dive equipment sellers will be able to tell you how to fit a scuba mask in 30 seconds. It is better, however, to understand the parts of the mask and how they effect the mask performance so that you can make an more informed purchased.
Major types of mask designs and their parts
You will hear different terms thrown around when talking about mask designs. You will hear people mention scuba mask, snorkeling mask, goggles (ouch), swim mask and freestyle mask. There are three basic functions that a mask must meet to be safe for scuba diving: The lens or face plate must be quality tempered glass, there must be a means to equalize pressure both of the mask and ears, and finally the mask should have low volume.
As mentioned, the function of a mask is to maintain an air pocket in front of the eyes. As we descend, the air pocket is compressed getting smaller and the outside water pressure is pushing against this. While diving, we need a mask that includes the nose inside it so that we can exhale slightly when needing to equalize the pressure. Lets get away from swim mask and goggles right away. Swim mask and goggle do not have this function. Diving with goggles at any depth can cause pain and black eyes or worst. Masks designed and marketed for snorkeling and free diving have different requirements, some may or may not meet the requirements. While you may hear divers say that a snorkeler’s mask is not acceptable, that is not always the case. In fact, some manufacturers that have separate snorkeling and scuba brands will sell the same mask under different brands.
You will also hear terms like frame or frame less, high and low volume. A mask, whether for scuba, snorkeling, or free diving, has four basic components. These are the face plate to see through, the skirt with a nose pocket to seal out water, a strap to keep the mask in position and a protective case for the surface. These pieces, except the case, can be held together by a frame, which allows them to be separated or molded together frame-less during manufacturing. Each has their benefits and drawbacks. A frame mask can be disassembled for cleaning and if a skirt needs to be replaced it is a simple task and less expensive then a new mask. Frame-less mask need to be replaced if damaged. They do, however, have a smaller volume and fold up smaller. A frame-less mask can be used as a back up mask fitting into a BCD pocket easily. A framed mask will not fit most BCD pockets.
If you wear glasses, before you purchase a mask you need to decide if you will get optical inserts for a mask or wear contacts. Framed mask allow for the replacement of the normal lens with prescription lens. Some mask manufactures make lenses in different prescriptions, while other mask can have custom lenses made to fit the mask. Frame-less mask do not have the option.
Volume refers to the amount of air inside the mask as you wear it. A low volume mask is important for scuba divers but critical for free divers. The lower the volume of a mask the less air is needed to equalize it and in case of flooding to clear it. While a scuba diver can exhale a few times to clear a mask or equalize it, a free diver only has the air in his lungs and any air used to equalize lessens the time they can stay down. Volume is not much of an issue for snorkelers as they are often at or near the surface, so pressure and clearing is not as critical.
The case that comes will a mask is often a hard plastic case that is designed to protect it from damage. A dive boat is a dangerous place for a fragile item as a mask. Weights get dropped, items slide of benches and hit the deck, and other carelessness can damage one. When not wearing your mask it should be kept in the case. Some manufacturers are now providing a mask bag instead of a hard case. These bags are padded to provide protection. While not needed to dive, it is a good practice to treat the case as a part of your dive equipment.
A dive mask can have a one lens design or a two lens design. It is more a matter of preference which one you should get. Trying diving with different mask with either one or two lenses. The visible difference is that there is no separation over the bridge of the nose. To some divers that makes a difference. The other major difference is that a single lens mask does not accept prescription lenses. You might also see what is called multi-lenses mask. These mask have lenses to the side as well. The most common shape of lenses for scuba diving is called the inverted tear drop. It is narrower at the bottom then top. This helps divers to see their gauges more clearly as they look down. Some mask will also rake the lenses so that the bottom is closer to the face. This also improves the ability to look down as well as reduce the volume of the mask.
The lenses of a scuba mask are tempered glass and you will see that on the lens. Tempered glass is made so that if it breaks, it crumples instead of breaking into sharp shards. This reducing the chance of eye injury. Impurities within the glass, mostly iron, will impact on the ability of the mask to pass light without altering it or reflecting it. These impurities can give a slight green tint. Most dive mask have an 80 to 90% transmission range. This is more than adequate for most divers. The very best mask, and especially those designed for underwater photographers may use lenses with a 95% transmission rate.
Some lower quality snorkeling mask use plastic lenses. These are not acceptable for scuba as it will not withstand the pressure or handling that a scuba mask must. Some high quality, and high cost free diving mask also uses a type of optical plastic. While safe for depths, they have not yet proven the durability that temper glass has.
The quality of the skirt is one of the major points when purchasing a mask. Not only will the quality impact how long a scuba mask will work, it also allows the mask to accept a wider range of facial features and still provide a seal. Medical grade silicon is the material that skirts are made of, sometimes with additives to prevent damage from UV rays or mold. Medical grade silicon is more pliable than other grades such as food grade which may be found in other mask. This improves flexible of the edge leading to a better seal. A skirt has a double edge to provide two layers of sealing, and most have a secondary skirt that increases the surface area against your face. As mentioned before, a diver needs to be able to equalize their ears. This is done by pinching the nose and gently blowing air out the nose. To hold the nose closed, the skirt has a pocket for the nose built-in that is soft enough to be squeeze closed.
The strap attaches to the scuba mask by a buckle arrangement so that the strap can be adjusted. The point of attachment is either the frame or close to the lenses to reduce the pressure on the skirt near the seal. The strap is of the same material as the skirt, however, many divers will either cover the strap or replace it for greater comfort.
How To Find The Perfect Scuba Mask
The perfect scuba mask is the one that meets your requirements and is a perfect fit. The most important point is that the mask fits your face. You will have done this when you started your training but it bears a quick review. When trying on a mask, make sure that all of your hair is away from your face. Even one small hair can break a seal. Move the strap to the front of the mask, position the mask to your face and inhale. As you do, try to sense if air is coming into the mask. Remove your hand and hold your breath. If the mask is properly sealed, it will stay in place until you exhale. Some people will find it difficult to hold the mask in place even with a seal as they tend to exhale slightly when they stop inhaling. So give it a few tries if it seems to you that is what is happening. Most people will leave the test there, however, there are a few additional steps you should do. Put the mask on as you would for a dive. Adjust the straps so that they are holding the mask in place. Remember the strap is to keep the mask in position and has little to do with creating a seal. Tightening the mask to much can cause the skirt to buckle and create a leak. Give yourself a few minutes to get use to breathing only through your mouth and note if the mask feels comfortable. Does it press against the nose? Do you feel that it is either too large or small for your face? Are you comfortable with the vision? If it does not meet your approval 100%, try another. One last test is to clear your ears. Can you comfortably pinch your nose close, using either hand? If you plan to wear gloves, then also try it wearing gloves.
Before Your First Dive
A new scuba mask will have a film over the lens that results from the manufacturing process. This needs to be cleaned off before you dive or your mask will fog. Before you jump and clean the mask listening to the old timers, read your owners manual. The experienced divers will often tell you to use toothpaste to clean your mask. Well mask and toothpaste have changed over the years. Some mask have special coated lenses that will be ruined by the toothpaste process. Some toothpastes have whiteners that can damage the silicon. So read the owners manual and see what is appropriate for your mask, and yes some manufacturers still do recommend toothpaste. Baby shampoo is also widely recommended.
With proper care that includes placing the mask in the case when not wearing, a mask can last decades.