I bought a bucket of sarco oil putty 4 years ago,I had glazed one busted window,,,it was a job just to get the bucket open from the top seal and gasket,after job done,I resealed it ,, knocking the top down till it seemed a tight seal a year later I opened it again,, the top inch and a half or so had hardened solid,,I thought crap why did itt dry out?,, what I did today after removing the hard chunks big and small pieces, was use a qtr in drill with 2 allen wrenches tightened snug into the drill mouth,, then use some lemon oil as a softening agent mixing the stuff until the whole bucket ( 2/3s remaining) was again soft restored of oil,it mixed nicely when I finished a plastic bag covered the open bucket,,it sealed seccurely I think it will remain pliablle and ready for use whenever.
One thing I like to do is to put about 1” of distilled water over the top of the putty in the bucket. It gets a skin on the top that you need to peel off, but it will stay good and not dry for a good few years from my experience.
