Cyanotype photography with potassium ferrocyanide

Some years ago, due to a translation error that I only discovered later, I made cyanotypes using a mixture of ammonium ferric citrate and potassium ferr**o**cyanide instead of ferr**i**cyanide. This worked, although they seemed to be less sensitive (reacted slower to sunlight) than the guide I was trying to follow, but I didn't have a way to measure.


*Is it safe to make this substitution?* (I have lots left over and it would be good if I could use them up)


*Is the resulting blue pigment the same Prussian blue as would result from using potassium ferricyanide?* (some of the pigment seemed to wash away, whereas the guide said that only the unreacted reagents would do so)


*Is there really a difference in sensitivity between this mixture and the ferricyanide mixture?*


