So Im getting into the darkroom and trying to figure it all out on my own (the internet has been a great tool). After realizing it was silly to attempt to print with rodinol... I was doing some printing last night, here was the setup - Ilford Multigrade Dev - 1+19 Dilution - Mixed up 600ML - 60 second Dev time (it was hot in the dark room) - Ilford Stop Bath - Ilford Rapid Fixer - Ilford multi-grade RC Pearl paper - 8x10 in 8x10 trays The test prints went along quite nicely, ended up needing to do 2 to figure out the timing. Third print at the proper exposure was spot on. However the fourth print seemed a bit lighter. Every thing else was held constant, was I running out of developer? Is there any rule of thumb, hard numbers, (soft numbers) lose estimations or data on how many prints you can get per volume of developer?