I've been using postcards in may paintings since the 1990s. My selections have evolved over the years. When I began it was interesting to connect two disparate scenes, adding a third and a fourth. In some cases I used scores of cards to create a new and enveloping space.
I preferred the cards that had no borders so I could make them disappear. In these paintings the eye could drift from one card to the next seamlessly. Horizon lines became irregular and at times references to cubism emerged. Later it became interesting to capture the card perspective and construct a more convincing whole. Interior scenes with picture windows (and pictures in frames) could be created. Museum spaces were alluded to at times. As a challenge I made a conscious effort to use cards with borders and strong graphic divisions within them to construct another kind of space -- a kind of modernist reference to Kandinsky, Stuart Davis, Mondrian, Leger, and others.
As always the painting starts easily and finished slow. Like all painters I worry about the upper left hand corner and the lower right. My problems may be solved by finding just the right card and that invokes shuffling through my considerable and unorganized collection. I tend to stay away from really beautiful collectable cards. Out of respect.
For more on WW's postcard paintings, have a look at the new book William Wegman: Painting, which features essays from Bob Elliott, Martin Filler, Amy Hempel, Robert Krulwich, and Susan Orlean.