Digital BW, The Print

Hello

Thanks to everybody on this forum who warned me not to try to dilute 
my dried up 25% grey (forgot to put the lid on the bottle)any longer. 
 As I have ordered an EPSON 2100 I am not too keen on ordering fresh 
quadtone ink for my 1160 from the States.

But I still have plenty of 100% / 75% / 50% ink which should be ok. 
Any suggestions how I could make a decent 25% grey using either of 
them? (I think Paul Roark in the early days of developing the 
"variable mix quadtone set" worked with dilutions of original inks.
Or 
was it just mixing???)

Thanks for your help

mathias muenger (switzerland)