Re: I need some help with airtightness
Or you could try a piece of fabric - PYH gave me the tip. I wrapped a piece of dampened flanne (form cut to fit the stem seat) around the base of the stem and jammed it on the base jar. Gave a great seal! Works much better than my papertowel/foil fix.
Another "temp" seal would be the plumber's tape - no adeshive residue to clean up.