There is a LOT of information around windows available from the National Trust for Historic Preservation's Preservation Green Lab, which you can google.
In many states (if you're in the US), your State Historic Preservation Office will have someone who can point you at local resources about working with old sashes.
I would actively NOT recommend doing anything involving spray-in foam insulation, because it's likely to harm more than it helps. Also it is an absolute bear to scrape off things so you can fix them properly later.
If you're looking for a relatively quick fix, heavy insulated drapes can do a lot for you until you can figure out the best longer-term solution.
no subject
In many states (if you're in the US), your State Historic Preservation Office will have someone who can point you at local resources about working with old sashes.
I would actively NOT recommend doing anything involving spray-in foam insulation, because it's likely to harm more than it helps. Also it is an absolute bear to scrape off things so you can fix them properly later.
If you're looking for a relatively quick fix, heavy insulated drapes can do a lot for you until you can figure out the best longer-term solution.