As a means of reproduction, stenciling dates back thousands of years — tens of thousands if you include cave paintings of hands.
While it’s an ancient practice, stenciling continues to have tremendous modern relevance, especially with new techniques afforded by digital cutting tools now available to stencil artists.
Stenciling is an important creative tool for practices as diverse as street art (Figure A) and surface mount soldering.
Bridges and Islands
A stencil is a tool that selectively allows passage of some material to create text or designs. While pigment is the most commonly stenciled material, other products such as solder may also be applied in this way. Stencils allow passage through holes cut out in the material, such as paper, plastic, cloth, metal, etc. More elaborate designs can be created through the use of bridges and islands (Figure B).
You can cut stencils by hand, but tools to create stencils from digital images have become increasingly common, so let’s learn how to use a digital cutting machine (Figure C) such as a Cricut, Silhouette, or CNC router with a drag knife to create a stencil, and then apply that design with spray paint.
It’s an important first step to determine how complex of a stencil you want, and if you want to be able to reuse it. Digital cutting machines are commonly used with adhesive backed vinyl. This offers the potential for stencils that have islands without bridges, allowing very complex designs. The trade-off is that these stencils are not reusable. If you want to stencil the image again, you cut another one on your tool.
Vector vs. Raster
In this skill builder we’ll make a one-shot stencil without bridges on adhesive vinyl and a multiuse stencil on cardstock. For simplicity’s sake, we’ll focus on a single color stencil. We’ll use Inkscape (inkscape.org), a free tool that runs on Windows, Linux, and Mac OSX, to create our images. Inkscape works with SVG natively. SVG is a vector image format and is importable with the Cricut and Silhouette cutting software. Inkscape can also export DXF, which is a more universal format for vector data. Vector images are defined by lines rather than pixels, so they can scale without any loss. Pixel-based formats such as JPG, GIF, BMP, and PNG are raster formats (Figure D, left, alongside a vector image, right) and can be converted to vector images in Inkscape with a tracing function.
Stenciling is a black and white operation. In other words, it’s like a binary — either the pigment will pass through a section of the stencil or it will not. Not all images translate to this 1-bit mode very well. Line art and text do extremely well, but photographs usually have the most trouble. Converting an image to pure black and white is often referred to as setting a threshold (Figure E). Tools like GIMP and Photoshop are excellent for this. Vector tools like Illustrator or Inkscape can set the threshold as part of the tracing process.
One-Shot or Reusable
Regardless of the tools you use to construct your stencil image, you have to determine the answer to the question asked earlier: one-shot or reusable? A one-shot stencil can have islands without bridges (Figure F). You cut the stencil on adhesive vinyl, adhere it to your target surface, and paint over it. When the paint is dry, you remove the vinyl and reveal the stencil. This process can create extremely detailed stencils at the cost of having to cut a new one for each use.
A reusable stencil (Figure G) has to be contained on a single sheet. The islands must have bridges to hold them in place. This reduces the complexity of the stencil and introduces considerations like how well supported small protrusions are and how flimsy the spacing is between items. Generally, you can solve these issues by reducing the detail level of the stencil.
Cutting a reusable stencil requires thought about the material you’re cutting. Cardstock is useful, but can tear or get soggy with too much paint. Acetate or other plastic sheets are strong but may cause dripping since they don’t absorb any of the paint. I generally prefer using plastic sheets (sold as report covers at the office supply store) and just using a light touch with the spray paint (Figure H).
Cutting the stencil on any of the commercially available cutting machines is extremely simple. Load up the program you want to use (Silhouette Studio, Cricut Design Space, and Craft Room are very common) and import your image. It’s possible to import vector designs into these tools, but I prefer to import a raster and let the cutting software trace it, because it eliminates a lot of frustration I used to have with hidden and redundant objects in my vector files.
With the image traced, select the appropriate material you’re going to cut. Adhesive vinyl usually comes in a roll that you feed into the cutter. Plastic sheet or cardstock is attached to a cutting mat that has a light adhesive which holds it in place. Your software will provide a dialog to select the material and select the presence or lack of a cutting mat. You should also verify that the right cutting tool has been selected. The most important consideration is the thickness, which relates to the depth of cut (Figure I). Ideally you want to cut the vinyl or stock and not the backing sheet or cutting mat.
Applying Adhesive Stencils
Adhesive vinyl stencils have a multistep process for application (Figure J, shown as a gallery):
- Pick out the parts that need to be removed to let paint pass
- Adhere transfer paper to the entire stencil (it’s like super-wide masking tape)
- Remove backing sheet and adhere the sticky side of the vinyl to the target. Burnish and remove transfer sheet.
- Mask around the edges with paper and tape
- Spray or sponge paint evenly onto the stencil
- Once dry, remove the stencil. Stand back and admire.
Stencils cut on materials using the cutting mat can just be peeled off for use. If thin parts of the stencil break, or you find that small sections lift off the surface when painting, you can make repairs or enhancements. As you lift away sections of the stencil, move in the same direction as the smaller extrusions, which will help them lay flat instead of pulling them up inadvertently (Figure K).
You can tape breaks, trimming the excess tape away with a utility knife, and you can reinforce parts that lift by taping thread, a wire tie, or a toothpick onto them. You can also assist a stencil’s adhesion by cutting holes in areas that you use as a place to apply tape (Figure L).
Stenciling can be done with spray paint, sponged paint, chalk, and other media. Be careful not to let parts of the stencil lift away from your surface when applying your medium, which can cause fuzzy lines. Also be careful when moving the stencil — wet paint under or on the stencil can easily be smeared. If you’re using the one-shot vinyl approach, let the paint fully dry before removing the vinyl. Consider putting a coat of clear finish on top of your work to help protect it from scratches.
With stenciling, always remember to be considerate of where you paint your designs, and have fun!
While stencils are generally intended for a single color, they can be created to work in groups, one per color, to create multicolor images (Figure M). Breaking an image into different colored stencils that work together is a task that can be done in image editing programs. Once it comes to the stencil itself, alignment (or registration) of the multiple stencils and the order in which they are applied are the only differences between single and multicolor images.
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