I developed my technique for layered Acrylic Collage by a series of happy accidents. I was gluing gold composition leaf to a canvas and the metal turned green and blue. It took me two years to stabilize the process so make materials that could be rolled, folded, and cut out with scissors.
The process takes a month to make and cure the acrylic materials. I use about 20 different kinds of metals and 7 different acrylic mediums. I create layers of acrylic mediums, a texture layer (usually leaves, because they are free) and a layer of metal leaf. I place more layers of medium over the metals and the colors come up spontaneously. I add two layers of acrylic varnish and then cure the material for two weeks, which deepens the colors. The colors come up according to the weather...humidity, temperature, and air movement. Once cured, the acrylic material does not change color again.
I have tested it in sunshine for over a year. The acrylic materials are ten layers deep and do look different at different angles and under different light. When people buy my collages in the parks, I warn them that the artwork will look different at home under incandescent or fluorescent light.
Every time I think I can control the results, the material shows me something new. I embellish my collages with purchased glass, beads, wire, and threads. I paint my own "frames" on the wrapped canvas and cradled wood because any purchased frame looks dead against the depth of the materials. I have recently begun adding my own kiln-fused glass.
My goal is to make as much original material as possible to use in my collages.