The trouyble may well be the acrylic...when acrylic dries it's insoluable in water or just about anything else.
I would suggest that you look into the Shiva Casein mediums and colors that are now made by the Jack Richeson Company and easily available through Dick Blick and others. I paint in caseins every now and then and they seem to be an "antique process" even for painters.
The only other thing that i might suggest is using watercolor instead of acrylic or just good old plain pigment.
Best wishes with this...I remember reading about this process some time ago in the days of my photographic youth.
Stay connected and tighten your budget with a great mobile device for under $50. Take a Peek! (http://pr.atwola.com/promoclk/100122638x1221845911x1201401556/aol?redir=http://www.getpeek.com/aol)