"In 1784, the much-admired French sculptor Jean Antoine Houdon agreed to execute a full-length marble statue of George Washington for the Virginia State Capitol in Richmond, and he traveled to America the following year to make a life mask of his subject. In addition to serving as an aid in completing the final marble statue, the mask became the basis for many plaster and terra-cotta busts of Washington, including this one. Houdon fashioned the first of these smaller likenesses while still in the United States, and before returning to France he presented it to Washington. The marble statue took some ten years to complete and still resides in the Virginia Capitol." -- National Portrait Gallery
Benson Lossing portrayed Houdon's bust of Washington in his 1859 book, Mount Vernon and Its Associations Historical Biographical and Pictorial.
This photo of Houdon's Life Mask of Washington appeared in Memoirs of the Life and Works of Jean Antoine Houdon The Sculptor of Voltaire and Washington by Charles Henry Hart and Edward Biddle, 1911, between pages 202 and 203.
See more about the full length marble statue in Richmond.
For other portraits of Washington see, The Portrait Gallery: George Washington