I used to begin a painting on a blank, white piece of watercolor paper, but when I switched to acrylic painting and acrylic marbling in 2007, I often found it easier to start with blobs of amorphous color and create a painting that had several layers of color peeking through. This method creates depth, mystery, and a bit of happenstance---I don't know what my finished painting is going to look like, but that's part of the excitement. I feel driven, energized, and compelled to keep going as I respond to what is happening on the paper. Some of my best paintings have arisen out of this process because I just LET GO of the outcome and concentrate on PAINTING.
When I marble papers that have been previously painted (in watercolor or acrylic), I layer new colors and patterns over old color. I often start with the back of a watercolor "test" page (blobs or marks of color are on the paper in a random fashion). Several of my artist friends have given me their old "junk" paintings to marble in exchange for one of my finished paintings. I sometimes wipe off some of the watercolor paint with a sponge before preparing the paper for the marbling tray. My aim is to marble in a way that obscures most of the original image, but still gives me a few little random shapes to deal with when I set about to finish the painting.
I've included two examples of this process--one is a finished landscape by artist Alisha Whitman, which I marbled, cropped, and over-painted, turning it into vase of greenery. The other started as a watercolor "test" paper from artist Leslie Dugas (which I turned into a figure). This is one of my favorite ways to paint on my marbled papers and turn old subject matter into something completely different. Obviously, I don't enter these "collaborative" pieces into juried shows (whose rules insist on the work being done by one artist), but these experimental paintings push me to innovate and improvise--what more could an artist ask for?