Mirror Demisters

A demister is a flat heating pad fixed to the back of a mirror, either bonded on during manufacturing or fitted behind an existing mirror as a separate panel. It gently warms the glass surface a few degrees above room temperature, which stops steam from condensing on it the way it would on a cold, unheated mirror. The effect is a mirror that stays clear through a shower rather than fogging up and needing to be wiped before use.

Some demister pads can be retrofitted behind an existing mirror if there's enough clearance and access to run power to that wall location, but it depends on how the mirror is currently mounted and whether a suitable pad is available in the right size. It's generally more straightforward, and often a cleaner result, to choose a mirror with the demister pad already integrated during manufacturing than to retrofit one after the fact. A licensed electrician can advise which approach suits your specific mirror and wall.

Yes, always. A demister pad runs on mains power, so connecting it involves wiring into the bathroom's electrical circuit, which in Australia has to be done by a licensed electrician regardless of how the mirror itself is mounted. The circuit also needs to meet bathroom safety requirements, since it's operating in a wet area. This applies whether the demister is factory-integrated into a new mirror or added as a separate retrofit panel.

A demister pad draws relatively little power compared with other bathroom electrical fixtures, since it only needs to keep the glass a few degrees warmer than the surrounding air rather than heat a room. Many households wire it to the same switch as the bathroom exhaust fan or a dedicated switch near the door, so it can run for the duration of a shower and switch off afterwards rather than being left on continuously. Confirm the recommended operating pattern with your electrician, since wiring setups vary by home.

A demister and an exhaust fan solve slightly different problems. An exhaust fan clears steam from the room over time, but a mirror can still fog in the minutes before the room fully clears, especially in a smaller or poorly ventilated bathroom. A demister keeps the mirror itself clear throughout the shower regardless of how quickly the room airs out, which is the main advantage if you shave or check your appearance immediately after showering. In a large, well-ventilated bathroom the benefit is smaller, since the mirror may clear on its own reasonably quickly anyway.

Not automatically, though many do, since both features already require a mains power connection and are commonly bundled together on the same mirror. It's worth checking the specific product rather than assuming, as some LED mirrors are lighting-only. If a plain mirror with just a demister and no lighting is what you're after, that's also a straightforward option, since the two features are independent of each other.