Well it worked, to a certain degree.
Unused ink jet photo paper accepts all the colours I used. Rinsing needs to be gentle. Black ink is transient and wants to slide off the surface, but will dry and adhere if the lifting and flattening process is fast enough and without rinsing. I used degreaser as the surfactant, spacing the colours with it when I worked monochrome.
Once out of the ink trough, the water puddles on the surface of the paper and gives another oppportunity for the application of more ink.
Largest sizes worked to A2. Will try A1 and A0 on Monday
See uploaded images.