Audio: How did sculptors make wax models?

How exactly did sculptors make wax models? V& A curator Peta Motture explains:

Peta Motture:
What artists would do is to take the wax and add into it some animal fat, which would make it malleable, and a little bit of turpentine that would enable it to just give it a little bit of strength. And if they then wanted to work in a colour, like this one is red, they would add something like red earth or vermillion and they'd grind this up, put it in the molten wax, then when the wax had cooled down they made little rods and from those they were able to pick off pieces of the wax and add bit by bit to the model. In some cases you would work the wax around an armature, a central support that could be wood - in this case it's metal, it's just a metal rod. You didn't have to do that, but that's what Michelangelo did in this particular case and that way it gave it some kind of strength and stability. And the fascinating thing as well about Michelangelo and this model in particular in relation to the marble that was ultimately made from it, was that it shows exactly how he worked.

Female narrator:
Models would often have been kept in the sculptor's studio after the design was finalised. According to the sixteenth century artist and writer, Giorgio Vasari, in his 'Life of Michelangelo', sculptors also used models during the marble carving process.

Male voice:
'One must take a figure of wax or some other material and lay it horizontally in a vessel of water; then, as the water is, of course, flat and level, when the figure is raised little by little above the surface the most salient parts are revealed first, while the lower parts (on the underside of the figure) remain submerged, until eventually it all comes into view. In the same way figures must be carved out of marble by the chisel; the parts in highest relief must be revealed first and then little by little the lower parts. And this method can be seen to have been followed by Michelangelo in his statues of the prisoners.'