Cleaning the mirror

During the observations I did last week, I saw that there were some black spots on my mirror.  So today, I put my mirror in the shower and cleaned it.

I started rinsing the mirror with normal water.  I was happy that I could already see that most of the black spots disappeared. The second step was to add one drop of a cleaning product.  I then cleaned the mirror with cottonwood, by applying little pressure.  I finished by rinsing the mirror with demineralised water.  A very successful action, because the mirror looks again like new.

The mirror with the black spots (if you really look carefully).