Some time back there was a thread on removing hardened window glazing compound. The primary tool discussed was a heat gun. I am faced with the removal of glazing compound but discovered that the term I needed to search on was "putty softener". Doing so gives the following:
The CRL Putty Softener who price is given above has a "home" web site of
Doing the Google search on "putty softner" will give several more but I didn't look beyond the above. Happy unputteying...