If this is Matte Black (MK) I have experienced this same problem on my Epson R1900. The Matte Black ink does not bind well no matter which side of the paper you use or what kind of paper it is. I have used two approaches to solving this. My first method was to spray the print with fixative. This solves the smearing but involves an extra step, and I detest aerosols. A better solution was to add a GL (gloss) curve to match the MK curve (Copy curve from: MK; I set the GL limit about 10% higher than MK). This adds just enough of the glosser to bind the Matte Black without giving a noticeable gloss. I use this on both glossy photo paper and matte papers (usually watercolor paper). Cheers!