Why It Happens
The dome forms because water expands ~8% when freezing, and the center freezes last, pushing upward. A container on an uneven freezer shelf, or overfilled past MAX, amplifies the effect. The dome can prevent the lid from closing or hit the blade unevenly at the start.
How to Fix It
- Small dome (under 5mm): process normally, the first scrape levels it.
- Large dome hitting the lid: let soften 10 minutes, press gently flat with a spoon, refreeze 30 minutes.
- Never cut the dome off with a knife: you risk scratching the container.
How to Prevent It
- Fill only to MAX line — leave the expansion space above.
- Freeze on a perfectly flat, level shelf (check with a spirit level once).
- Tap the container on the counter 4-5 times before freezing to release trapped air.
- Cover with the lid: the dome grows larger in uncovered containers.
Frequently Asked Questions
Why does my frozen base always have a hump in the middle?
Water expands 8% when freezing and the center freezes last, pushing upward. Fill to MAX only, freeze flat, and tap out air bubbles before freezing.
Does the dome damage the blade?
A small dome does not. A tall hard dome makes the blade hit unevenly at first contact, straining the motor. Flatten large domes before processing.
When should the lid go on during freezing?
For the first hours the tub goes in the freezer WITHOUT the lid, perfectly level: the cold reaches the surface and it sets flat. Once the base has set you can close it, to keep out odours and frost, until the 24 hours at −18 °C are up.