The special qualities of acrylic paints allowed Mac a completely new way of working. The brilliant colors are easily mixed with water in batches, and lay down flat on the canvas.   They dry fast, and once dry they are no longer water soluble.  Mistakes or unanticipated effects can easily be corrected, and new layers immediately added on top. Working quickly, artists can mix wet into wet with acrylics, and some of Mac’s early acrylics show quite a bit of brushwork.  But adapting to the paints, she soon began to create works that look as if they had just appeared on their own without any visible help from the artist at all.  

Acrylics also work well with masking tape.  Mac's windows and doors, porches and shutters were almost all created by taping around an area, painting in the desired color, letting it dry and stripping the tape.  You simply can’t do this with oils or casein.

Mac painted each acrylic fairly quickly, but then she meditated on them over an extended period of time, sometimes years. She partially or completely repainted numerous paintings, changing the colors, eliminating unnecessary detail, and refining silhouettes. She worked on Doorway to the Sea for ten years.