By Magnus von Kageneck, cellar master · Updated: August 2026
Something smells odd in the cellar — now what? The good news first: of the three most common wine faults, two can be cured and the third can be prevented. The bad news: all three get worse the longer you politely pretend not to smell them. Welcome to the clinic, in order of frequency.
1. Reduction — rotten eggs from the fermenter
Smell: rotten egg, garlic, burnt rubber.
Cause: the yeast has been under stress — usually from a lack of nutrients in the second half of fermentation — and is producing hydrogen sulphide.
Rescue: in its mild form it blows off with aeration: rack the young wine vigorously two or three times (racking with air contact, for once!). Whatever still stinks after two weeks needs copper treatment — at that point it is a job for a specialist supplier, not for the home-remedy shelf.
Prevention: yeast nutrient from the start, and for high-sugar batches a second dose after a few days. It costs pennies and saves the vintage.
2. Film yeast — the white film
Appearance: first isolated white islands on the wine, later a continuous, wrinkled skin.
Cause: air. Film yeasts are harmless but greedy surface yeasts — they eat alcohol and leave behind a flat, musty wine. They almost always turn up after fermentation, in vessels that are not filled to the bung.
Rescue: caught early, it is a cosmetic problem: carefully skim off the skin, draw the wine off from below the surface (place the tube beneath the film), fill the new vessel to the brim and stabilise it with sulphur.
Prevention: after fermentation, always keep vessels full to the bung — make up any shortfall with a smaller vessel or glass marbles. After fermentation, air is no longer your friend.
3. Acetic spoilage — the only total write-off
Smell: sharp and vinegary, often with a note of glue (ethyl acetate).
Cause: acetic acid bacteria, carried in by fruit flies or unclean vessels, plus air.
Rescue: here I have to be honest — there is none. Once acetic acid is in the wine, it cannot be removed. A slightly affected wine can still be drunk up without delay; a pronounced case of acetic spoilage has only one dignified future left: give it a vinegar mother and deliberately turn it into what it wanted to become anyway. Lost wine makes excellent vinegar — here is how.
Prevention: cleanliness, an airlock from day one, take fruit flies seriously, never leave partly fermented leftovers standing open next to the fermenter.
The cellar rule behind it all
Almost every wine fault is a story about air or about hunger. Keep the yeast fed, keep the finished wine away from air — and the clinic stays empty. And if something does smell: act early. A wine almost always forgives quick intervention, and almost never forgives waiting.
Related in the shop: Yeast Nutrients & Fermentation Aids and Making Wine