PE is correct from a pure technical point, however in a home darkroom we often make concessions due mainly to space, cost and being practical.
I myself use Jobo graduates, they are plastic and virtually impermeable to contamination from photographic chemicals. If they weren't, then I would have been in trouble many years ago.
I do though follow PE's advice regarding using a set of graduates for developers, another for bleach and fix solutions, plus another set for stabiliser and Photo-Flow solutions.
I have mixed up E6, C41, B&W and a myriad of other kinds of solutions using about 12 different graduates. I did start to use glass about 15 years ago, but due to a lack of feeling in my hands and fingers, I started to drop things and started to break them, so I reverted back to my plastic graduates.
I also use my Durst Printo paper processor for Colour negative paper prints, as well as B&W negative paper prints. I have switched back and forth over the last 18 or so years I have had the machine with no discernible problems. That doesn't mean that one could not measure a cross contamination, it is just that I haven't noticed any and none of my prints that have been processed have shown any problems, although from a scientific point of view, this practice would be unacceptable.
From a home processing point of view, I would suggest you do whatever you can afford. If at a later stage you really swing into colour processing, then outlay some dosh and get another set of graduates and go from there.
One point of view in this debate about single use graduates, are the film developing tanks available today. The great majority are plastic, very, very few are stainless steel. Virtually everyone switches from B&W to C41 to E6 to whatever in the same tank!
Mick.
