GEBHARDT recommends freezing plates in a chamber at least 5 °C below the melting point: -8 °C for a -3 °C plate, -19 °C for -14 °C, -23 °C for -18 °C and -26 °C for a -21 °C plate, with 24 hours in every row. A chamber colder than that threshold shortens the time, and a warmer one does not freeze the plate through.
Heat flow grows with the difference between plate and air, while the chamber's power, its fill and the airflow inside the rack cap the gain. The display setting can differ from the real temperature at rack level, so the measurement is taken with a logger beside the rack.
- Start with the same plate model and the same layout
- Record real air temperature, chamber fill, and in and out times
- Confirm complete freezing by the filling turning solid
- Change the chamber by one degree and repeat the same cycle
The difference shows over a week of records rather than two cycles; the measurement is repeated for a new load or a new chamber layout.
