Spectacles
Cleaned more often than anything else a person owns, almost always on a shirt tail, which is the one method the lens manufacturer names as damaging.
Precautions
- Test on an inconspicuous area first
- Check the manufacturer's instructions
Start here
What this is, what tends to go wrong with it, and what to do about it.
Made from
The science behind this: Mechanical action and abrasion
In detail
Spectacles are probably the most frequently cleaned object anybody owns, and the usual method is the one the lens maker singles out. Wiping them on a shirt, a tie or a tissue is called out by name, and the reason is the everyday dirt trapped in the fabric, which scratches the lens and risks damaging the coating. What makes this worth spelling out is that there is no recovery. Scratches cannot be wiped away from plastic or glass lenses; a scratched lens is replaced. Almost every other cleaning problem has a remedial step, and this does not, so the whole answer is about not causing the one event. The cloth is the variable that matters most. A reusable cloth accumulates the same abrasive particles as clothing, so a favourite microfibre kept in a pocket is not automatically the safe option; cloths are not to be washed above 40°C or with fabric softener, both of which leave them worse than before. Heat is a separate hazard: extremes of temperature are advised against, with a car on a hot day given as the example.
Related
- Spectacles is made from Coated spectacle lens
Sources for this page
Sources
Lens and Screen Cleaning: how to clean your glasses
Carl Zeiss Vision · Manufacturer documentation
Relied on for: That reaching for a tissue, tie or sleeve is called out by name because trapped dirt scratches the lens and risks damaging the coating, that reusable cloths retain abrasive particles, that cloths must not be washed above 40C or with fabric softener, that scratches cannot be removed and scratched lenses should be replaced, and that extremes of temperature are to be avoided. (states this directly)