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Something else not in that article.
AR coatings are sensitive to three things:
1. They have microscopic pores which allow water molecules from the air to get in between the coating and the glass substrate. End result is small pieces flake off. This is often visible with aluminium mirror coatings after several years. Wash only when its really necessary.
2. Thermal shock - the result being that the coating will either start to craze (fine hairline cracks) or possibly pieces flake off the glass substrate entirely. With coated spectacle lenses, putting them in hot water (out of a tap) is enough to trigger this. With astro objectives and correctors, I'd have to say go easy with the hairdryer as a means of removing dew, you may find the coating suffers as well.
3. Whatever is in DEET and Aerogard insect repellant will cause permanent damage to coatings. Use a roll-on, or if you must use a spray, do it downwind of all the scopes and nowhere near your eyepieces or camera lenses.
Last edited by Wavytone; 22-12-2018 at 11:00 AM.
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