I just finished temperature drop measurements with 38°C water in a 1520 Jobo tank, here is the test setup and the results:
Here's the results:
0:00 38°C
0:30 38°C
1:00 38.2°C
1:30 38.2°C
2:00 38.2°C
2:30 38.2°C
3:00 38.2°C
3:30 38.0°C
4:00 38.0°C
4:30 37.9°C
5:00 37.8°C
5:30 37.8°C
6:00 37.8°C
6:30 37.6°C
7:00 37.6°C
7:30 37.5°C
8:00 37.4°C
8:30 37.4°C
9:00 37.2°C
9:30 37.2°C
10:00 37.2°C
- Jobo 1520 Tank with both film spools but no film
- Tank preheated by filling it with 38°C water twice and leaving it in the tank for 30 seconds both times (which is incidentally the method PhotoEngineer recommends for preheating)
- No efforts made to keep the tank warm, I just put it on my washing machine during the experiment
- The thermometer is a color thermometer with 0.2°C scale resolution
- The thermometer would stay in the film tank, which means the lid was open throughout the test.
- After 25 seconds I cycled the tank for 5 seconds to simulate agitation - note I couldn't tilt the tank because there was no lid on it.
- This 25 + 5 second step was repeated 20 times for a total of 10 minutes.
- Room temperature was 28°C
Here's the results:
0:00 38°C
0:30 38°C
1:00 38.2°C
1:30 38.2°C
2:00 38.2°C
2:30 38.2°C
3:00 38.2°C
3:30 38.0°C
4:00 38.0°C
4:30 37.9°C
5:00 37.8°C
5:30 37.8°C
6:00 37.8°C
6:30 37.6°C
7:00 37.6°C
7:30 37.5°C
8:00 37.4°C
8:30 37.4°C
9:00 37.2°C
9:30 37.2°C
10:00 37.2°C