I'm going to make my first ziatype tomorrow. I'm going to start with a 4x5 neg. How many drops should I start with? I will be using cot320 & brush coating. The B&S kit instructions state 15 drops of ferric ammonium oxalate & an equal amount of lithium palladium for an 8x10. Will 4 drops of each be enough for a 4x5? When I put these drops in a shot glass, do I have to mix them up with something, or just swish them around?