Sourdough Starter Smells Like Nail Polish Remover (Acetone) — Why & How to Fix
Your starter is starving. Acetone is what active yeast produces when it's eaten everything in the jar and started consuming itself.
You open the jar and get hit with a sharp acetone or nail-polish smell. Maybe a bit of clear liquid (hooch) is sitting on top. The starter looks deflated.
What it looks like
- Sharp, solvent-like smell — acetone, nail-polish remover, or rubbing alcohol
- A clear, gray, or yellowish liquid layer on top (hooch)
- Starter has fallen — once domed, now flat with a few small bubbles
- Sometimes a thin crust on top, with the liquid underneath
Why this happens
Overdue for a feeding
The yeast and bacteria have metabolized all the available carbohydrates. With nothing left to eat, they produce acetone (the same compound found in nail polish remover) as a byproduct.
Feeding ratio too small for kitchen temp
If your kitchen is at 78°F and you're feeding 1:1:1, the starter peaks and crashes within 4–5 hours. By the next feeding, it's well into the starvation zone.
Long fridge stint without a refresh
A starter that's been in the fridge for two or three weeks will exhaust its food eventually, even when cold. Pull-out reveals the classic acetone smell.
How to fix it
Feed it immediately
Discard down to 25g and feed 1:5:5 (25g starter + 125g flour + 125g water). The extra-large feeding gives the yeast plenty to work with and helps mellow the acidity.
Double feed if it's been a while
After 24+ hours without food, feed once and let it peak (6–8 hours), then feed again. Two feedings 6–10 hours apart restore vigor faster than waiting longer between feedings.
Stir the hooch back in (or pour it off)
Stir for tangier bread, pour off for milder. The starter will still be active either way.
Preventing it next time
- Feed your starter on a schedule. Counter-kept: once or twice a day. Fridge: once a week.
- If your kitchen runs warm, increase the feeding ratio. 1:5:5 lasts longer than 1:2:2 at 78°F+.
- Mark the jar at feeding height so you can see when it has peaked and fallen.
Most starter problems show up in the data.
Sarah's Sourdough — the iOS app — logs every feeding, photographs every rise, and predicts peak by your kitchen temperature. Problems become visible weeks earlier.
No subscription. No ads. Yours forever.
Related problems
Liquid layer on top (hooch)
Hooch is alcohol. Yeast has metabolized all the available sugars in the flour and produced alcohol as a byproduct. Your starter is hungry, not dying.
Hasn't bubbled in 5 days
It's almost always temperature or chlorinated water — both kill wild yeast before it can establish.