I have a numbe rof rubber bungs.. one and two holed that fit my equipment/glassware perfectly.
After much use and years, they had gone hard, shiny due to oxidation...and wouldnt stay in the neck of the glass boiling flasks anymore. ( kept popping off)
Rather than throw them out, I have "restored" them.
This involved using some rough emery paper to scour the outside of the bung.. evenly all the way around.
Then a quick wash to remove the dust.
Dry well.
Then I wiped them with butan-2-ol. seems to work really well, and they have comne up like new.. I decided to use the butan-2 -ol , as I wanted a hydrocarbon that wasnt oily, but not metho or ethanol.
I will be really interssted in finding a better way to resore bungs.
What do you guys do/use?