They are frequently stated to be of beaten bronze, but they are really castings, apparently by the cire perdue process.
The vicomte de Spoelberch de Lovenjoul (1836-1907) was well known in France as the author of [[[Charles Augustin Sainte-Beuve|Sainte-Beuve]] inconnu (1901), La Genese d'un roman de Balzac (1901), Une Page perdue de H.
As early as the pyramid times solid casting by cire perdue was already used for figures: but the copper statues of Pepi and his son seem, by their thinness and the piecing together of the parts, to have been entirely hammered out.
By the time of the XIIth Dynasty, and perhaps earlier, cire perdue casting over an ash core became usual.
Their exact method is not certainly known, but it appears probable that they were acquainted with the process now called a cire perdue - the same as that employed by the great Italian artists in bronze.