Just posted this in a thread on another site, Thought I'd share it here . Join Date: Dec 2002 Location: Port Macquarie Posts: 256 All lenses, Spectacle, Camera, Binocular, Phone, Sounder Screens , lap top, computer , you name it. All collect airborne dust. Add to this sweat, oily skin, salt crystals from salt water. Wiping these surfaces with any dry tissue or cloth will damage the surface, Glass is far more resistant, until you put a coating on it ! Some are softer than glass. Cr39 lenses, ( plastic ) scratches much easier than glass, Most cr39 lenses these days have a hard coating put on them to help, and it does. Polycarbonate lenses all come with a hard coat as polycarbonate scratches very easily. Glass in spectacle lenses is obsolete now, It is not as safe as cr39 or polycarb breakage wise, Impact resistant. BUT polarised glass is laminated and much safer !!! Cr39 and polycarb are 1/3 the weight also, much more comfortable. SO dry wiping is out !!!!! As I have said, the best is Cold Soapy water and a tissue. The water washes the abrasive dust off , ths soap removes any oily skin residue, and the tissue dries it. But you cant wash your binoculars, camera, lar top. Thats where the lens wipes are good, or if soapy water isn't convenient. I have used Zeiss and Specsavers, Both work well, but the Zeiss being " Alcohol " based, dries too quickly in hot weather. The " soapy " specsavers is my preference. The other major destroyer of Sunglass and Spectacle lenses is HEAT, And it doesn't take a lot. Left in direct sunlight on an aluminium boat, or ANYWHERE in a hot car can damage the lenses!!!!!!!.There is a small amount of pressure to hold the lenses in a frame. enough to warp the lenses if they get hot. The hard coat I spoke of can craze, orange peel effect. Especially Polycarbonate lenses.Th expensive Multicoat, which removes reflections from the lens surface making it clearer to see through, Will craze. Any thing else you want to know ?? Howard.