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Life Hack: Defog your mirror


You know how it is when you’ve just stepped out of a lovely hot shower, all ready to look at yourself in the bathroom mirror but you can’t see a thing because the mirror is all fogged up? What are you going to do? Take a look at this hilarious video to find out the science behind this very common problem and how you can solve it!

Why does the mirror fog up?

Well, the mirror is colder than the air, so when the water vapour caused by your hot shower comes into contact with the mirror, the vapour cools to a liquid – otherwise known as condensation.

Now, the first thing most people try is frantically wiping away the fog with a towel. This usually leaves the mirror all streaky so you still can’t see in it properly. It also only solves it temporarily as the mirror soon steams back up again.

What is the solution?

The key to the solution is changing the temperature of the mirror so that it is warmer! Interestingly, some 5 star hotels get around this problem by installing a heater plate behind the mirror. This means the mirror is not the coldest thing in the room, making sure that the water vapour condenses elsewhere. Probably not the answer in most people’s homes though so the next best thing is the humble hairdryer!

Simply direct a blast of warm air onto the mirror and your mirror should not only clear but also stay fog-free as it is now warm and so not prone to condensation. Of course, it is viewed as a safety issue using electric hairdryers in a bathroom, so here are a few other ideas to try that don’t involve heating up the mirror. Simply apply your choice of fog-deterrent to the mirror and wipe away with a paper towel. You could try:

  • Shaving cream – this works because it creates a protective film over the glass which stops it fogging up. You don’t need to use much – just a little dab. Apparently, this method will ensure a fog-free mirror for up to three weeks!
  • Car wax will also work for similar reasons, as will liquid soap or shampoo
  • Vinegar and water solution – bit of a problem with the smell of vinegar there though!
  • Washing-up liquid –  this works in the same way as the shaving cream or car wax. If you’re a bit of a prankster you could write a secret message first to spook any future bathroom-users!

The main problem with all these methods though is that they need to be performed in advance, so the hairdryer still wins in the battle of the fogged-up mirror! And if all else fails, you could just open a window…


Do you spend time wondering how things work and why stuff happens?

Find out the answers to trivial stuff like this, as well as the more important questions like the meaning of life and the universe, by studying Maths and Physics A-levels!