Stan wrote:
Is there a way/method for extending the shelf life of Minwax Wood
Putty after the jar has been opened?

"__ Bob __" wrote

Open the lid .. blow in a little propane from a torch .. close the lid.
Propane, being heavier than air will sink to the bottom, effectively
keeping the oxygen away from the putty, which needs oxygen to cure/dry.

Of you could simply store the cans upside down.

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)