How to clean the inside of a windscreen without smears

Updated 3 November 2026 · 3 min read

The inside of the windscreen gets dirtier than most drivers realise, and you only notice when low winter sun or oncoming headlights turn the glass into a sheet of glare. A clean inside screen also mists up less, which matters in a climate as damp as ours.

Cleaning the inside of a windscreen is awkward rather than difficult. The glass is steeply angled, the dashboard is in the way and the film on the glass is greasy, so a quick wipe with a cloth usually just moves it around. The method below takes about ten minutes and gives a clear, streak-free result.

Where the film comes from

The haze on the inside of the windscreen builds up from several sources:

• Plastics and vinyl in the dashboard and trim release vapours over time, especially when the car heats up in the sun. These condense on the cool glass as a greasy film. It is more noticeable in newer cars.
• Breath and skin. Every time you breathe in the car, moisture and oils settle on the glass. Wiping misted glass with a hand or glove adds more.
• Smoke and vaping leave a stubborn residue.
• Dashboard sprays. Silicone-based dash shine products drift onto the glass.
• Air from outside, carrying traffic fumes and dust through the vents.

What you need

• Two or three clean microfibre cloths: one for washing and one or two for buffing dry. Keep them for glass only.
• A glass cleaner. If your windows have aftermarket tint film, use an ammonia-free cleaner, as ammonia can damage film.
• Optional: a long-handled windscreen cleaning tool with a pivoting pad, which helps reach the bottom corners.
• Optional: a little isopropyl alcohol diluted with water for very greasy glass.

The method, step by step

1. Park in the shade. Cleaner dries too quickly on warm glass and leaves streaks.
2. Dust first. Run a dry microfibre over the glass and the top of the dashboard to lift loose dust. Otherwise you will just make mud.
3. Spray the cloth, not the glass. Spraying the screen sends cleaner onto the dashboard and the instruments.
4. Work in sections. Clean one half of the screen at a time from the seat on that side. Wipe in overlapping straight strokes, first horizontally, then vertically, so you can see where you have missed.
5. Use the back of your hand to reach into the bottom corner where the glass meets the dash, with the cloth folded over your fingers.
6. Buff dry straight away with a fresh, dry microfibre. This is the step that gets rid of streaks.
7. Check from the driving position, ideally with the sun or a torch shining through the glass at an angle. Go over any smears again with the dry cloth.

Do the mirror, side windows and the rear screen while you are at it. On the rear screen, wipe along the direction of the heating lines rather than across them to avoid damaging the element. The same care applies to heated front windscreens.

How to stop the windscreen misting up

Ireland's mild, damp weather means the air inside a car is often humid, and the glass is often cooler than that air. Moisture condenses on the coldest surface, which is the windscreen. A clean screen helps, because condensation forms more readily on a dirty surface, but managing the moisture matters most:

• Use the air conditioning with the heater. The air-con dries the air before it reaches the glass. On most cars, selecting the windscreen demist setting switches the compressor on automatically. It works even in winter.
• Switch off recirculation once the car has cleared. Recirculated air holds the moisture from your breath and wet clothes.
• Dry the interior. Wet coats, umbrellas and soaked floor mats keep the air damp. Take mats out to dry and check for leaks if the carpets stay wet. See leaking windscreen.
• Replace the pollen (cabin) filter at the intervals in your service schedule. A clogged filter reduces airflow to the screen.
• Do not wipe the glass with your hand. Skin oils leave a smear that mists faster next time.

Safety first

Never set off with a misted or partly cleared windscreen. Wait until the demister has cleared the glass fully, or clear it with a clean cloth while parked. A clear view of the road is a legal requirement, and the condition of the glass, wipers and washers is also checked at the NCT. See will a cracked windscreen fail the NCT?

How often should you clean the inside?

Every few weeks is enough for most cars, and more often in autumn and winter when low sun and long nights make glare worse. If you notice the screen misting up more than usual, a clean is usually the first thing to try.