In the last exercise, painting the flower, the frisket was cut in a process of elimination. You removed area number 5 and painted it, then removed area number 4 and painted it without replacing frisket film number 5. This was continued until the entire process was completed achromatically. Then you sprayed a transparent color over this rendering to develop the image.
This procedure is fine as long as all the petals are meant to be the same color. However, if you were to paint petals number 5 red and petals number 4 blue, you would have to replace the frisket film over number 5 before painting number 4. This is to prevent one color from drifting into another. Replacing frisket film in exact registration can be extremely difficult. The slightest shift in registration when replacing the frisket will cause paint to fill in the gap and leave a line where you don’t want one or possibly cover some of the white paper on an adjoining area so no paint can be received, thus leaving a white area in the rendering.
To assure registration when replacing frisket film, use a simple process called a “flap system.” Here’s how to do it:
Cut the areas of frisket film you wish to render. When all areas are cut, take a small piece of drafting tape and lay it over a small area of the cut (half of the tape on the frisket you will lift and the other half on the frisket that stays in place).
When you lift up the frisket film to paint, it is now hinged with the tape. Simply fold back the hinge so the frisket is out of the way and then paint the area. Once the paint is dry, you can fit the flap of frisket back into place without any shift in its registration. This procedure can be continued, picking up the frisket and dropping it back into place until the entire rendering is complete.
TIP: When the piece of frisket is flapped back out of the way, the adhesive side is facing you. To prevent painting the adhesive side, take a small piece of the frisket backing paper and cover it. That way, when you airbrush, paint will not go onto the adhesive and ruin its tack. Practice this on the flower exercise. Hinge number 5’s, lift them, paint the area, then fit back into place. Repeat this process for areas 4, 3, 2 and 1.
The flap process will save you time and aggravation.