It is a common problem to experience fog in part or all of your masks while snorkeling or diving. Besides using your own spit or commercial D fog, there are a couple of common methods used by dive masters boat operators and frequent divers.
The first method is using white toothpaste.
Squirt a little bit on to each lens and rub it in. Be sure to use white toothpaste and not gel
It is important to rub the toothpasteinto each lens for several minutes. You will finish the process by rinsing thoroughly on each lens. A cotton swab may be used to remove any grit from the corners and crevices.
Be sure to remove every remaining bit of white toothpaste. This will ensure that if any water enters your mask. You will not get toothpaste in your eye. Tt is a good idea to repeat this process ever so often especially prior to your first outing of each trip.
The next method we involves mixing between 30 to 50 percent baby shampoo with water.
Find a small squirt bottle and fill it with baby shampoo to, about halfway full at the most. Then fill the other half with water. Replace the cap and shake up the bottle to mix the mixture.
Just before entering the water, spray a small amount onto each side of your mask. Rub the mixture on to each lens. You may do a quick dip to rinse or leave the mixture on the mask. Some boat operators will provide this mixture for you and a rinse bucket .
If your mass should flood while underwater, or if you do not have defog, you may leave a small amount of water at the base of your goggles.
If your mask fogs then lean forward to allow the water to wipe it clean. This concludes the common methods we have learned from scuba professionals on D fogging a mask.