Lens care · Explained by an optical technician
How to stop glasses fogging up
Why glasses fog up
Glasses fog when warm, humid air meets a cooler lens and condenses into microscopic water droplets. This happens with masks, hot drinks, cooking, gym sweat, and walking indoors from the cold.
Anti-fog treatments only work on a clean lens, because grease and fingerprints stop them from bonding evenly. Cleaning the lens first is the step most people skip, which is why their anti-fog spray wears off within hours.
Ways to stop glasses fogging
- Apply a dedicated anti-fog spray or wipe to clean, dry lenses.
- With a mask, fit it snugly over the bridge of the nose so warm breath cannot escape upward.
- Let glasses warm to room temperature before entering a warm building.
- Push glasses slightly down the nose to increase airflow behind the lens.
- Avoid breathing upward under scarves and high collars.
The step people forget: clean first
- Clean the lenses with an alcohol-free lens spray and a microfibre cloth so no grease remains.
- Let them dry fully.
- Then apply your anti-fog spray or wipe to the clean, dry lens for it to bond and last.
Note: Lensora is a lens cleaner, not an anti-fog product. It prepares a grease-free lens so an anti-fog treatment can actually adhere and work.
Frequently asked questions
Why do my glasses keep fogging up?
Glasses fog when warm, humid air hits a cooler lens and condenses into droplets. Common triggers are masks, hot drinks, cooking, exercise, and coming indoors from the cold. Anti-fog treatments and snug mask fit reduce it.
How do I stop my glasses fogging with a mask?
Fit the mask snugly over the bridge of your nose, using the nose wire if it has one, so warm breath cannot rise onto the lens. An anti-fog spray on clean, dry lenses also helps. Rest the glasses on top of the mask.
Does the soap trick stop glasses fogging?
A thin smear of washing-up liquid buffed off a lens can reduce fogging briefly, but it is short-lived and can streak coated lenses. A dedicated anti-fog product on a clean, dry lens lasts longer and is safer for coatings.
Why won't my anti-fog spray last?
Anti-fog spray does not last when it is applied over grease or fingerprints, because it cannot bond to a dirty lens. Clean the lens first with an alcohol-free cleaner, dry it fully, then apply the anti-fog treatment.
Does Lensora stop glasses fogging?
Lensora is a lens cleaner, not an anti-fog spray. It removes grease and fingerprints so an anti-fog treatment can bond evenly to a clean, dry lens. Cleaning first is what makes any anti-fog product work properly.
Anti-fog only works on a clean lens. Start with Lensora, then apply your anti-fog treatment.
Made by an optical technician. See the Everyday Lens Cleaning Kit →