When the cold sets in, condensation on windows becomes a frequent problem in many homes: foggy windows, and, in persistent cases, humidity and mold. A simple method that comes back every winter is to place a container of salt near the windows, a tip highlighted by the Spanish newspaper El Confidencial as an economical way to help “dry” the air near the glass.
Condensation appears when the warm, moist air inside comes into contact with cold surfaces, such as glass, and the water vapor turns into droplets. In addition to being a visual nuisance, it can keep areas damp for hours and create conditions for mold and deterioration of materials, especially in homes with poor ventilation.
The article states that, in cars, opening windows and renewing the air usually resolves quickly, but in a house, control is less immediate, because humidity comes from various routines: cooking, showering, drying clothes and even breathing at night. This is why low-effort “tricks” tend to gain popularity this time of year.
How the idea of salt near the glass works
The logic of the method is that of a “passive mini-dehumidifier” near the window: the salinity helps to attract/absorb moisture, reducing the water available in the air at that point and, in theory, reducing the formation of drops on the glass. This explanation is attributed in the text to expert Andy Ellis, cited by a British newspaper.
In practice, a low container (small bowl or jar) with table salt or coarse salt is recommended, adjusting the amount to the size of the window and keeping it close to the place where condensation is most visible. When the salt becomes damp and hard, it must be replaced to continue to have an effect.
The scientific basis can be described simply: concentrated saline solutions have lower “vapor pressure” than pure water, which favors the passage of moisture from the air into the system until it reaches equilibrium. It is a logic used in technical references of relative humidity with saturated saline solutions.
What this trick achieves (and what it doesn’t)
The trick can help in light and localized situations, mainly as a moisture “buffer” near the window, but it does not replace structural measures when there is daily condensation and mold. If the house has continuous sources of steam and little air renewal, the effect of a bowl of salt tends to be limited.
It is also important to understand that sodium chloride (common salt) has a hygroscopic behavior with a threshold: it only starts to absorb water in a more marked way and to form brine above a certain relative humidity (the so-called deliquescence point), referred to in the technical literature in the order of ~75–77% for NaCl. This means that, in many homes with moderate humidity, it may not be the most “aggressive” material to capture water.
If the objective is to cut humidity more effectively, the most consistent recommendations include regular ventilation (including short, intense ventilations), control of steam sources (kitchen and bath), and, when necessary, a dehumidifier. These measures attack the cause and not just the symptom on the glass.
Simple measures to reduce condensation and prevent damp
Ventilating remains the most important step: opening windows for a few minutes a day, using exhaust fans when cooking or showering and preventing moisture from “trapping” behind thick curtains or furniture against cold walls. Small, repeated habits often have more impact than any one-off trick.
According to , another strategy is to reduce the entry of cold air and increase thermal comfort near the windows: seals and watertight improvements can help stabilize the temperature of the glass and frame, reducing the thermal shock that favors condensation. However, when airtightness is improved, ventilation becomes even more crucial to avoid “trapping” vapor inside the home.
Finally, there is a gesture that makes a difference when condensation already appears: clean and dry the surfaces, to prevent water from remaining in contact with wood, silicone and walls for hours, creating conditions for mold and stains. The goal is to prevent a winter problem from turning into a health and home maintenance problem.
In short, the salt bowl can be a cheap and easy “patch” for moderate cases, but it works best as a complement to a basic set: ventilation, management of daily humidity and active mold prevention. It’s this combination, not a single trick, that often decides whether your windows spend the winter dry or constantly foggy.
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