Top tips from Bali Scuba – Preventing Mask Fogging when Diving.


A fogged mask is not just an annoying irritation, it can also be dangerous. If a diver cannot see clearly he cannot communicate with his buddy effectively and if his focus is on the fog in his mask it is likely that he will lose focus on his surroundings and buoyancy. The best time to deal with a fogged mask is before you go anywhere near the water.

Mask fogging

Mask fog is annoying and potentially dangerous if it limits your visibility

Let’s take a moment to look at why fogging occurs – the scientific bit!!

All air contains some humidity, or tiny particles of water. When we are wearing a scuba mask if we breath out through our nose (normally, or when clearing the mask) we add more moisture to the air inside the mask.

The humidity inside the mask condenses into tiny drops which fog the glass. Think about when you pour a cold drink from the fridge into a drinking glass – water droplets from on the outside of the glass. These drops of water come from the humidity in the air around the glass. The same situation occurs in your mask when the warm air you exhale touches the cold glass of the mask!

Mask fogging explained

Mask fog is annoying and potentially dangerous if it limits your visibility

Scientifically water molecules are able to hold themselves together and form the tiny droplets which make the fog. Mask de-fogging agents and some other solutions (read on below) work because they make it more difficult for the water to hold together, therefore no droplets and no fog!

When we are talking about masks fogging there are two different scenarios – one for dealing with a new scuba mask and another for dealing with a used scuba mask.

New Masks

New masks have a residue on the glass which is used during the manufacturing process to stop the glass from being scratched. This residue needs to be removed otherwise fogging will be a problem. These are the two most effective ways of removing residue from inside of the mask.

Scuba masks

Many styles of mask are now available but having a clear mask is most important

1. Toothpaste: Take a small amount of toothpaste on your finger tip and rub it around the inside of the mask without leaving any areas untouched. It may help to leave toothpaste in the mask overnight or to scrub the mask several times to allow the chemicals to react. Try not to use a whitening toothpaste as these often contain granules or crystals and these could scratch the glass.

2. Playing with Fire: Using a cigarette lighter run the flame of the lighter over the inside of the mask until it turns black. Don’t worry that the glass appears charred – it will wash off very easily. Be careful not to melt the silicone or rubber of the mask though. You may need to repeat this process a couple of times but be careful – both the mask glass and the lighter will become quite hot!

Used Masks

Even used masks need to be treated before every dive. If fogging is persistent or severe it may be an indication that there is still some manufacturing residue on the mask and so you should try either toothpaste or a flame again. For minor fogging make sure you defog before every dive:

1. Spit: This only works if it doesn’t dry out so you need to do it immediately before the dive. Spit in the mask and rub it around with your finger and then rinse briefly in fresh water. The spit prevent the water from forming droplets.

2. Commercial Defogging Agents: There are a range of these available on the market and usually they come in small handy sized bottles that will fit in your gear bag. Spray the glass according to the manufacturers guidelines.

3. Baby Shampoo: This is a great defogging agent – it is cheap and as it is designed for babies it will not sting during the dive if some gets washed into your eyes – you should rinse it out though before diving.

Cleaning scuba mask

Whether you choose spit, shampoo or toothpaste just rub into the glass with your fingertips

4. Glycerin Soaps and Dish Washing Detergents: Use these in the same way as baby shampoo – just rub some into the glass and then rinse out. Unlike baby shampoo, dish washing soap will sting your eyes!

5. Toothpaste: Toothpaste can also be used as a defogging agent before every dive. Rub a small pea-sized amount in to the glass and rinse before diving – minty fresh eyesight!!

If anyone knows of any other ways to prevent mask fog let us know! Having a clear mask can make the difference between a safe and enjoyable dive or a dive which is not fun, and potentially dangerous.