When you make a multi-layer stencil, you typically want to get more colors or more tones than you get in a single-layer stencil. But if you use all the stencils and cover all of a rectangular surface area with paint, you end up with something that looks more like a painted postcard than a work of art. So, we recommend leaving out one of the stencil layers and allowing the surface color to come through instead. It creates a good effect when the surface color comes through.
When you use the Bay Stencil stencil maker and we ship you stencils, we ship you stencils that cover the whole rectangular surface of the image you uploaded. But you typically get a better result if you leave out the stencil layer that represents the color most closely matching your surface color.

Using the surface color means fewer bridges to clean up, and a ‘floating’ effect of the image on the surface.
That’s especially cool if you have a really rich yellow school bus paint.
Occasionally, there are details in the surface-matching color stencil layer, and you want to selectively add just a few of those details. In this example, although the wall color is white, and we are leaving out the white layer, you may want to use the spots on the white layer that are on the interior of the stencil to add in a few bright spots on the bus (like where the sunlight is reflecting off the surface). That way, even if your surface isn’t bright white, you can still have patches of bright white on the interior of your image.