@StefanSzekeres Just not too hard and not ever on Lithium or other high energy batteries - some types of battery can explode if the casing damaged.

As a motorcyclist I used to wipe the inside of my visor with a little washing up liquid on a tissue once a month or so which did the trick. Some scuba divers spit in their masks before a dive which works but doesn't last as well.

My answer has been deleted - presumably as too OOB, (Out Of Box), but the question that I was trying to raise, in a light manner, is why would you worry when there are so many - much more immediate - possible sorts of infection when staying away from home? BTW where is the unsubscribe button?

Note that there was some fuss in the UK a few years ago when Rolls-Royce sacked a young employee who had been using a mix of Evo-Stick and Super Glue to hold his spiky style in place on the grounds that there was a risk of him damaging the paintwork and of his hair causing injury to co-workers. IIRC the industrial tribunal found for Rolls-Royce.