Cover the surface of the jam in the jar with a wax disc - this will help prevent mold forming during storage. (thespruce.com)
Well, this could be a clear sign of a moisture problem in the house, or mold forming which could be a big problem. (topchoice-homeinspections.com)
Naturally, their home becomes the site of a number of troubling and inexplicable occurrences: locked doors blow open, mold forms in unusual places, etc.. (dvdizzy.com)