American colonial paints were made using natural pigments, which were usually coarsely ground (and often unevenly ground). Colors available were typically limited to black, white, gray, tan, yellow ochre, red, green, and dark blue.
Green paints were made using copper compounds (a modern-day equivalent would be a chromium green). Reds were based on iron oxide (today used in paints such as Venetian red and Mars red).
Oil, egg (for tempera), and milk (for casein paint) were mixed with the pigments as a binder. Because the pigment was coarse and unevent, the paint was unevent and not a smooth flat color like modern-day paints. Brushstrokes were often also visible because of the round bristle brushes used.
How to Get an Authentic Colonial Feel
Remember the colors of colonial-era America were hand made; every batch of paint was made by a craftsman based on his own recipes and experience. Variations in color occured even within the same project. It's not like today where you can buy can after can of identical paint.
If you want to get an authentic Colonial feel, restrict your choice of colors to those mentioned. Various companies produce heritage paints, such as Heritage Village Colors and Milk Paint. Be sure to read the tips on using heritage paint before you buy.
Colonial floor stencils were commonly done in black, red, green, and white on a pumpkin-colored floor, either the natural color of the wood or one that had been painted with yellow ochre. (Mix some in with the varnish; acrylic paint if you're using water-based polyurethane and oil paint if you're using oil-based).
Add a bit of raw umber to your colors for an instant 'old' look, as well as using a slight stain in the final varnish. For an instant 'faded' look, thin the paint (but not so much it seeps in under the stencil), and wipe some of it off with a cloth.
