This hint comes from professional siding installers: When working with pre-painted wood or engineered-wood siding, paint the tops of coil-stock galvanized nails to match the color of the house before loading them into the coil gun. It’ll save you loads of time, as you won’t have to go back and paint all of the nail heads after installing the siding.
It’s best to use a 3-in. foam brush to apply the paint or stain to the nail coil. The small foam brush will spread the color evenly without excess dripping over the edges of the nail heads. Be sure to allow the paint or stain to dry completely before loading the coils into the nail gun.