Reverse painting on glass

Am interested in input for conservation of reverse paintings on
glass. Family heirloom--large painting of Heidelberg castle done
circa 1800. This is a reverse painting directly on glass that has
begun to flake. Have not opened back of frame for fear of the many
flakes that will fall out.  Restoration is probably not an option
due to expense, but would like information from conservators who
have experience in stopping deterioration and preventing future
damage.  Painting is stored in household environment but is
currently being protected from light and heat and is not on display.
Thanks for the input,

G. Lay

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                  Conservation DistList Instance 10:60
                  Distributed: Friday, January 3, 1997
                       Message Id: cdl-10-60-010
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