First of all the good news is that I've completed my second darkroom printing session in my bathroom. Results are not too bad at all!
At the moment my focus is to get understand exposure and contrast control.
What I'm worried about is the temperature of the developer. I mixed the developer at 23 C degrees. After 2 hours I measured the temperature of the developer tray, and it was 16 C. How to understand exposure and contrast if the developer temperature is not constant?
The prints look fine, anyway. Some people say that temperature deviation can be corrected by development time, but I haven't found any chart about this. I use Ilford Multigrade IV RC paper and Multigrade developer, I develop for 50 secs.
What is the truth?