A simple household item—washing-up liquid—can stop window condensation from forming, according to a journalist who tested the method at home. The trick, which costs as little as 62p for a bottle, eliminates the need to wipe down windows every morning.
Why condensation forms
Condensation appears when warm, humid air meets a cold glass surface. Warmer air holds more moisture, which builds up through everyday activities like cooking or showering, while colder air retains considerably less. As temperatures drop overnight, window glass cools quickly, and the surrounding air cools enough to turn into water droplets on the pane.
Leaving condensation on windows is inadvisable because it can lead to damp and mould, creating a more serious problem later. The usual advice is to wipe it away with a dry cloth to protect the frames and surrounding area. However, this trick tackles the issue at its source.
How the test worked
Mia O'Hare, a senior spare time journalist, treated only one half of her window with a small amount of washing-up liquid on a cloth, leaving the other side untouched. The next morning, condensation had formed on the window, but the treated side remained completely clear. The science is straightforward: washing-up liquid reduces the surface tension of water, forming a protective barrier on the glass that stops moisture from gathering into droplets.
O'Hare cautioned against applying too much, as it can leave smears. After using the method for a week, it continued to perform well, and she plans to apply it to all her windows through the winter.
Step-by-step method
To try it, use a clean, dry cloth and a drop of washing-up liquid. Squeeze a small amount onto the cloth, wipe it across the inside of the window pane to cover the entire surface, then buff it in to avoid streaking. Allow the solution to dry completely and avoid touching the glass. Reapply every week or so if condensation begins to return.
