~Having a mask fog during a dive can be an annoyance and stressful
It’s easy to avoid stress and the annoyance of a fogging mask if you follow some basic steps. When you get a new mask, check and follow the instructions for proper cleaning. Not all masks need to be prepped to remove a residue that occurs during the manufacturing process, follow the recommended cleaning procedures. For example, don’t use an abrasive scrub on a lens that has been treated with a “fog-free” coating because you could ruin a brand new mask.
Masks need to be cleaned regularly and defog applied prior to each dive. There are a number of commercial defog products available that are gel, spray or liquid and should be applied before each dive. Follow instructions. There is a method that can work in a pinch, spitting on the lens, rubbing the saliva around, and rinsing. While not completely hygienic, it does work when nothing else is available.
Did you know that sometimes, even with defog, a mask can still fog at depth? This can occur when the mask lens or lenses heat up. How does this happen? There are a number of ways you can heat up a mask lens or senses: 1) leaving a mask in direct sunlight, 2) putting the mask on your head, and 3) when the diver exhales through the nose during a dive. Three habits to avoid.
Remember these and see clearly.