"An old method of removing gunk from laboratory glassware was to swirl sand around inside it." I have a book about household management written by a butler who buttled for the gentry for decades. To clean wine residue and gunk from decanters, he recommends pouring the shot from a shotgun cartridge into the decanter and swirling it with water. I suppose sand would do if you did not have access to shotgun toting aristocrats.