I'm having a little trouble with my rag mat board surface holding up to all the color pencil layers. One thing I've found: odorless mineral spirits when allowed to over saturate breaks down my surface. I've since switched back to good old regular mineral spirits, but the damage was already done. -Came close to starting all over, but was able to dip and dab color where needed. The detailing is just about impossible. Working fixative allows a little repair. Otherwise, the piece is coming along. I will never return to odorless mineral spirits. Thank goodness for windows and fans!