The 16" ion milled primary mirror of my RCOS was cleaned March 13, 2010, initially
using a spray-on polymer compound made for first surface mirrors, followed by a
more standard water/Windex/detergent cleaning afterwards. Below left is a photo of
the cleaned mirror. It looks relatively ok, but there are signs of coating deterioration.
At the time I debated whether to send the mirror in for re-coating at Spectrum
Coatings, but decided to wait. However, at the end of the year I had the mirror out of
the scope again as part of installing a new mount, and I took advantage of this to send
the primary in for re-coating with Spectrum's MAX-"R" EAL film. After cleaning, the
secondary appeared to be in very good condition, so I did not send it in. Below is a
photo of the packaging, which consisted of a cardboard box lined with 1/8" plywood
to create an inner box of wood. Inside this inner box there was 4" of foamboard on
top and bottom, and a form fitting cutout of foam board in the center holding the
The mirror was returned to me 10 days after shipping to Spectrum. There is a big
difference in the appearance of the mirror after recoating (top left image). Although
the ever-present dust is visible after recoating, the new surface makes the absence of
the haze that was on the surface before recoating very noticeable.
cleaning, March 2010
Mirror ready to be
reinstalled after recoating
by Spectrum Coatings,
Secondary reinstalled after
cleaning, December 2010.
Some additional collimation
and rotation tests