Can dirty old demijohns be cleaned enough to be safely used for wine making? These two here have been up in the attic for many years, open with no top on. They've also spent some month sat outside with no top on. I bought two different sorts of bottle brush (one a specially angled one) and could try milton cleaning solution and lots of scrubbing. Would this be enough? Any tips? Or am I wasting my time and I should get new ones instead?