Foggy mask and goggle lenses are a common frustration among fans of water sports. Believe it or not, there really are some defogging methods that work reliably.
Why Do Lenses Fog? It’s Not Just About Condensation
Most people know the fog is generally caused by condensation, but they may not know that an effective defogger doesn’t actually stop condensation from happening. Due to differences in temperature and moisture inside versus outside your mask or goggles, it’s simply not possible to prevent condensation. Rather, the goal of any defogging method is to prevent the micro droplets of moisture from clinging to the lens in a fine, misty sheet. This is accomplished with “surfactants”: substances that lower surface tension between the droplets and the lens so the droplets slide down and off the lens as quickly as they form.
Defog Coatings Don’t Last Forever
Some dive masks and swim goggles are treated with a defogger before they leave the factory, but it’s important to know that defogging treatments are always temporary. Liquid, gel and sheet-type defogging treatments will all lose their effectiveness over time and must be reapplied.
Defogging Pro Tip: Start With A Clean Lens
Whatever method or product you use to defog your lenses, it’s crucial to begin with a clean, dry lens. Mineral deposits, body oils, sweat, dust, sand and other impurities prevent defog treatments from adhering completely to the lens. Even brand new masks and goggles often arrive with traces of lubricants and adhesives that were used in the manufacturing process, and these will also interfere with defogging.
Before applying any defog treatment or film, wash your mask or goggle lenses thoroughly with a gentle soap that doesn’t have any added moisturizers or conditioners that could leave a film behind. Baby shampoo or a basic liquid hand soap are both fine for this purpose. Rinse with clean, fresh (not salt) water.
Defogging Pro Tip: Defog Won’t Adhere To Wet Spots
If you’ve got a mask or pair of goggles with a couple of stubborn spots that always seem to fog up even when the rest of the lens is clear, it’s probably because those spots still had moisture on them when you applied your defogger. Drying everything completely is key to a successful defog treatment that lasts. If using a cloth instead of air to dry off, ensure it’s a microfiber or chamois type of cloth that won’t leave lint or tiny bits of fuzz behind.
Defog Options: From Spit To Film
Whichever of the following defog methods you choose, it’s critical that you don’t touch the lens once your defogger has been applied and your lens(es) rinsed. Body oils from your fingers will interfere with the surfactant effect. It's also important not to rest your mask or goggles on your head between uses to avoid transferring oils, gel or conditioner from your hair to the lens(es). Finally, avoid leaving your treated mask or goggles in direct sun between uses, as heat can break down your defog treatment.
You’ve probably seen divers and swimmers spit onto their lenses, rub the spit around and then rinse in the closest water, whether it’s salt water, pool water or fresh water. This method does work, but the “treatment” won’t last very long—generally only one dive or couple of swims--and some people find it distasteful.
2. Commercial Defogger Liquids and Gels
A commercial defog liquid is essentially a chemically engineered surfactant, so you know it will be effective. One of the advantages of using a defog liquid is that it’s easy to get complete, even coverage. Tusa View Super Anti-Fog Treatment comes in a special, sponge tip applicator bottle for touch-free application. McNett’s Sea Gold Anti-Fog Gel is applied with the fingertips.
Commercial defoggers like these can last through multiple dives and swims over a span of days, provided the user rinses the mask or goggles gently in fresh water after each use and avoids touching the treated surface.
3. Commercial Defogger Film
Most of us are familiar with screen protectors on our phones and tablets, and defogger films for dive masks work the same way: a clear layer of specially engineered film is applied directly to the clean, dry lens. TUSA Freedom Film is available for both single and double lens masks, and uses friction rather than any kind of adhesive, so the film is reusable and there’s no worry about sticky residue being left behind.
Like liquids, defogger films can keep lenses clear through multiple dives or swims for several days, but the user must be careful not to dislodge the film when rinsing and again, to avoid touching the treated surface.
A lasting, crystal clear underwater view is both possible and easy to achieve.