Interesting. I was not aware how useful freon could be for head cleaning, or even optical cleaning:

http://www.mcphersoninc.com/cleaningofmirrorsandgratings.htm

http://alemis.us.airliquide.com/ChemSafe/MSDS/Image/27868_1.pdf

But as I stated in my previous post, it has been many, many years since that stuff was bottled up. I cannot imagine that it has span that length of time with zero degradation.