In order to screen the heart onto the figure I made a quick mask using a sheet of overlapping masking tape onto which I drew a heart and then cut it out with a craft knife. Then I affixed that sheet of tape to the back of a small embroidery hooped screen.
Small screen for heart image
Close-up Of Second Screened Heart Image
Since I had two more T-shirts to screen, I had to wash out the screen between printings so that the ink wouldn't set up and ruin the screen. The washing process loosened the tape significantly and it was difficult to execute a clear print by the thrid screening.
Today I set about searching the Internet for silk screen masks and found that Speedball carries rather reasonable products that mask and will clean out of the screen with soap and water when desired. The ones that most interest me are the Speedball Screen Drawing Fluid and Speedball Screen Filler. First a design can be drawn onto the screen with a brush using Screen Drawing Fluid. When that is dry, the Screen Filler is applied. When the Screen Filler is completely dry, cold water washes out the Screen Drawing Fluid but leaves the Screen Filler and then the screen is masked and ready to use.
Super! I've ordered one bottle of each of these items and will write about their effectiveness when I use them. These items are available on-line at various sites; however, I ordered mine from Dick Blick.
I also found a tremendous site that gives detailed instructions on various silk screening techniques including step by step instructions on how to use the Drawing Fluid and the Screen filler. If you're interested, check out: http://www.reuels.com/reuls/Silk_Screen_Printing_Instructions.html.