In the early and mid-20th Century, metal advertising signs painted with enamel paint were ubiquitous. Though advertising evolved to use paper-based resources in place of metal, that type of signage is still popular on roadways and in communities. Metal is an excellent canvas for enamel paint and it is surprisingly easy to acquire. Though you may not notice sheets of metal for sale all the time, many hardware and craft stores carry them.
Choose a piece of metal for your sign. Aluminium and tin will be the easiest types to find, and both are excellent choices for this project.
Sand the metal with sandpaper to remove any roughness or blemishes, if necessary. Spray or rinse the metal with water to remove sanding debris. Let the metal dry completely.
Determine the layout of the sign. Use stencils to help you maintain uniformity and precision in your painting. Draw a sketch of your sign, if necessary.
Apply a coat of enamel paint primer to the entire surface of the sign with a brush or an aerosol spray can. Follow the manufacturer's instructions to determine drying time before painting your design.
Pour the paints onto a tray or pan, if you are using canned paint. Shake the cans according to the manufacturer's specifications, if you are using spray paint.
Apply a base coat to the surface of the metal to make the background. Use any colour in any arrangement you prefer but keep in mind the need for your signage to be legible, so use contrasting colours for the background and the sign text.
Follow the manufacturer's instructions to determine drying time. Wait overnight to ensure complete setting of the paint.
Hold a stencil to the surface of the metal. Paint in the letter or shape. Repeat this process all over the sign to achieve the wording or design you planned.
Allow the paint to dry according to the manufacturer's instructions. Wait overnight, if you can.
Touch-up the paint to strengthen the colours, if desired.