Hi Albert,
Dan is correct about linseed oil finishes. They can turn very dark over time but ebonized finishes were also used particularly during the 16th and 17th centuries. Usually the finish hid light colored fruitwood and offered a stunning backdrop for bone, mother of pearl and metal inlay. In addition, some utility and military guns were painted black. For example, I think British sea service muskets during the mid-1700s were often painted black.
dave