Digital BW, The Print

I'm going to do some experiments with ultratones and my 2100 soon.
I'll need to use empty color cartridges for refilling since there are
no virgin empties for this printer yet. I was wondering if any of you
know the best way to clean them out before i refill them? Is it
possible to use water for this or should I use some special celaning
fluids? I know I'm not supposed to do this, but I'm both curious and
impatient, so I'll at least make an attempt.

Thanks!