Thanks to the bad weather, I challenged myself to clean the primary mirror of my Newtonian. After two years the operation was probably overdue. I hope I haven't caused any damage!
The images show the operations sequence, same order as Greek-Latin writing:
1. mirror disassembled and dry blown (it was dirtier at the beginning)
2. mirror nest after removing the retaining clips and the mirror. Take any jewellery off your hands, to avoid scratching inadvertently the mirror! Next time I will use latex gloves as suggested by Tom in the comments below.
3. mirror after the first rinse with a simple jet of tap water, still dirty!
4. washing with a mild dish soap solution, followed by a gentle underwater swipe with cotton wool balls. I used a clean bowl instead of sink, that retains traces of fat.
5. blowing to remove the drops of distilled water used for rinsing, instead of buffering with tissue. Operations 4 and 5 were repeated 3 times.
6. the clean mirror screwed back onto the base. I hope I tightened the clamp screws correctly. Over-tightening may easily cause mirror deformation and therefore elongated stars at the edges of the images. It is common practice to put provisionally a business card as a spacer between the clamps and the mirror while tightening the screws, in order to prevent excessive strain.
Do not forget collimation after reassembling.
I hope this can serve as a reference for other serial mirror cleaners, in preparation for the pollen season, which is fast approaching!
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