Mix 1 cup of paint thinner to 1 gallon of exterior paint to help thin the paint out. The exact ratio is not critical, however. Mix the paint and thinner with a paint stick.
Apply a thin layer of paint to the surface of the wood with a paint sponge. Overlap each stoke by 50 percent to achieve a consistent layer of paint. Wait 10 to 15 minutes before moving on.
Wipe the paint off the surface of the wood with a clean rag. Follow the grain of the wood while wiping the paint off. This removes the excess paint and leaves the paint in the wood grain.
Inspect the wood after 24 hours' drying time. If you feel you want the color darker, repeat the process a second time.