Ice cream typically doesn't freeze solid in a refrigerator's freezer due to a few factors:
Temperature: While a refrigerator's freezer is cold, it is not as cold as the temperatures needed to freeze ice cream solid. The temperature in a typical home freezer is around 0°F (-18°C), which is suitable for storing frozen foods but not ideal for freezing ice cream solid. Ice cream requires much lower temperatures to freeze completely.
Freezer cycling: Refrigerator freezers often have a cycle where they alternate between freezing and defrosting to maintain a stable temperature. These cycles can cause fluctuations in temperature, preventing the ice cream from freezing solid.
Air circulation: Most refrigerator freezers have a design that prioritizes air circulation to keep the contents evenly chilled. This constant airflow can prevent ice cream from freezing solid because it encourages the formation of small ice crystals rather than a solid mass.
To achieve the proper freezing of ice cream, it typically needs to be placed in a freezer that can maintain a constant temperature below 0°F (-18°C). Commercial ice cream freezers or deep freezers can reach these lower temperatures and provide the ideal conditions for freezing ice cream solid.