Cleaning car windows outside: how do you remove the film?

For clear exterior windows, remove sand and heavy dirt first. Then loosen the film with glass cleaner and a clean glass towel. A second, dry towel removes the final residue. If streaks remain, check the towels, wipers and type of deposit before using ever more cleaner.

What is on the glass?

A smearable film can consist of road grime, oily residue or transferred care products. Small, clearly defined pale spots may instead be mineral deposits. Insect residue and tar are different types of contamination again. One cleaner will not necessarily remove all of them equally well.

Also check whether the streaks really are on the outside. Look through the glass after cleaning its exterior. A greasy film on the inside will remain; see our guide to Cleaning car windows on the inside.

How to clean without streaks

1. Work on cool glass in the shade: Hot glass makes cleaner dry too quickly. Have two clean towels ready, reserved exclusively for glass.
2. Remove coarse particles: Thoroughly rinse heavily soiled glass as part of the car wash first. Do not push sand across the glass with a dry towel.
3. Apply cleaner sparingly: On actual exterior glass, you can lightly spray Glas Reiniger Pro directly or apply it to the towel. Consider wind and nearby sensitive surfaces. Let it work for a few seconds without drying.
4. Loosen the film: Clean section by section with the first Carbon glass towel. Fold the towel and frequently switch to a clean side.
5. Wipe dry: Remove remaining residue with the second towel. Change it if it becomes damp or dirty.
6. Inspect under angled light: Different viewing angles reveal streaks more clearly than looking straight at the glass. Include the edges.

Why does the film return?

The same dirt is often redistributed during the second wipe. A towel previously used to remove wax or paint protection is therefore unsuitable for glass cleaning. Keep glass towels separate and avoid fabric softener. We explain their care in How to wash microfibre towels.

If streaks only reappear when the wipers run in the next rain, inspect their rubber edges too. Clean glass and dirty or worn blades are a poor combination. See Windscreen wipers leaving streaks for straightforward troubleshooting.

What if glass cleaner is not enough?

If bonded deposits remain, rubbing harder with the glass towel is a poor solution. Mineral residue may require a suitable remover; tar may need a material-compatible specialist cleaner. In each case, compatibility with existing glass coatings matters. Completely remove any residue afterwards.

Scratches are not dirt film. We explain the limits of glass polishing in Polishing a windscreen. Particularly within the driver’s field of vision, a specialist should assess whether correction is appropriate.

Cleaning and coating are separate steps

Apply a glass coating only to properly prepared glass. It does not remove film or repair scratches or faulty wipers. Vehicle manufacturers may restrict windscreen application, for example because of cameras or wiper behaviour. Follow these instructions.

If a glass coating is suitable for your vehicle, Coating car windows guides you through preparation and application. For regular cleaning, start with a suitable cleaner-and-towel combination.

Frequently asked questions