Depends on the specific paper etc. Test any safelight. I would personally NEVER handle any kind of
color paper except in total darkness. And RA4 chem does not keep well at all once it is mixed from
concentate. I won't mix more than I need for a single session, daily. You might relax these rules a
bit, but unless you have some scientific replenishment regimen, you might see a gradual degradation
in the quality of color if the chem gets stale. It's easy enough to mix in small batches. Temperature
control is vital for consistent results. That's simple if you have a tempering box or decent water
bath. I recommend Kodak RA/RT chemistry, though there might be acceptable substitutes. I've
never personally had good luck with "room temp" kits. I use 2 min times at 85F in drums. Be careful
to have good ventilation. Open trays can be a bit nasty on your lungs, and harder to keep constant
temp unless they too are suspended in a water jacket.