How to clean and store sunglass lenses without ruining the coatings

Why dry cleaning ruins lenses

Most scratches on a lens are not caused by accidents but by dust. A dry cloth pushed across a dusty lens drags mineral grit over the coating and leaves fine concentric marks that catch the light. Shirt hems, paper tissues and car wipes are worse, because their fibres are stiff and often carry oils. The rule is simple: nothing dry ever touches a lens, and nothing touches it before the dust has been rinsed away.

The routine that works

Rinse both sides under lukewarm running water so the grit floats off. Put one drop of neutral washing-up liquid on each fingertip, work it gently over the lens in circles, then rinse again until the water runs clear. Dry with a clean microfibre cloth using light pressure, holding the lens by the rim rather than pressing on the centre. Wash the microfibre cloth itself every few weeks without softener, because softener leaves a film that smears rather than cleans.

What never to use

Avoid alcohol, acetone, ammonia, window cleaner and anything sold for screens with a solvent base: they attack anti-reflective stacks and can lift mirror coatings at the edges. Hot water above roughly forty degrees is equally risky, since coatings and lens material expand at different rates and craze into a faint web of lines. Never leave glasses on a car dashboard in summer for the same reason, and never lay them lens-down on any surface.

Vintage and mineral lenses

Older mineral glass lenses resist scratching far better than modern plastics, but their coatings are more fragile and their gaskets, when present, can dry out. Gradient tints and old mirrored finishes should be cleaned with water and the lightest possible touch, without soaking the frame. On LUNETOS listings state whether lenses are original, replaced or ready for prescription glazing, which tells you how careful to be and whether a replacement is realistic at all.

Storage is half the job

Store frames in a hard case, folded, with the lenses facing up and a soft cloth between them if the case is tight. A pouch alone protects against dust but not against pressure in a bag. Keep them away from radiators and closed cars, and avoid hanging them on a collar for long periods, since that stretches the temples outwards and loosens the fit. Good storage costs nothing and preserves more value than any polishing product.