If you're interested in what appears to be THE best lens cleaning technique, have a look at Astronomy Now magazine's January 2017 edition (published this week in the UK) and the 3 page article documenting 'First Contact' polymer cleaning. The principle is similar to the OptiClean polymer lens cleaning method, but the various 'First Contact' kits provide additional options for 'stubborn' soiling including a liquid pre-treatment, special applicators. 'O' rings and lifting tools - latter to remove the polymer after it has 'set'. Astronomy Now magazine's Steve Ringwood cleaned several different optics including an ancient 1970s 5.25" refractor, a 50mm Lanthanum eyepiece, and a 10" diameter primary mirror which had been stored in a damp garden shed with resultant debris soiling. The soiled mirror lens cleaned up beautifully. First Contact, manufactured by Photonic Cleaning Technologies, is used to clean the LIGO gravity wave detector. The kits are expensive i.e. £88.40 and upwards http://www.365astronomy.com/Photonic...-Technologies/ (but note sample bottle sufficient for a few small lenses £4.80) but enable cleaning standards far in excess of that possible with regular liquid cleaners and micro fibre cloths. The cleaning polymer is not suitable for plastic lenses.