We're getting ready to repaint our "kit home" built approximately 1890. My husband removed the intricate scrollwork on the pillars, and we discovered that it's a rose-colored plaster cast. It's extremely soft, almost like chalk. What is the best way to remove over 100 years of paint without damaging the plaster? The paint has got to be almost 1/4 inch thick, and hides a lot of the design.