Following is a typical media and a typical way of testing the light exposure.

Single sided frosted Mylar (drafting Mylar used for technical drawings) can be used to make stencils with a variety of media. The density of the pigment will effect the exposure times thus a step exposure test is needed to find the exposure time that is right for your stencil/drawing. Almost any painting or drawing media can be used such as graphite pencils, gouache, china markers, acrylic paint and sharpies. Following is the procedure for testing the correct exposure for a Toner-Wash drawing made onto single sided Drafting Mylar:

1. Paint or draw directly onto the frosted side of the Mylar. This is referred to as your stencil or positive.
2. Place stencil frosted side down on ImagOn laminated plate in the exposure unit.
3. Set vacuum frame down. (or close contact frame)
4. Expose for 5 seconds or 5 unit increments. (Longer exposure units for Quartz Halogen Lamps)

5. Cover 1/4 of image with mat board and expose for 5 more units. Cover 1/4 more so that 1/2 of image is now covered, expose for 5 more units. Cover 1/4 more so that 3/4 of image is now covered and expose for 5 units more. There should be 4 different exposure times of 5, 10, 15 and 20 units.

6. Do a standard still development for 9 minutes, heat set in heating cabinet, vinegar fix, wash and dry the plate.
7. Pull a print and decide which area of the print closely resembles the stencil. More than one test may be required to get better results.