HODINKEE: What do the notches on the periphery of the pallet fork bridge do? Are they to adjust tension on the blades?
Stéphane von Gunten: Exactly. These two levers are used to put the blades in compression. With the right compression the system becomes bi-stable. By switching from one stable position to the other, a small amount of energy is given to the balance wheel at each alternance [vibration].
HODINKEE: Is there any functional benefit to having different thicknesses of silicon oxide deposition on the pallet fork and escape wheel?
Stéphane von Gunten: The utility of the [silicon] dioxide layer is to have a low frictional coefficient between the wheel and the pallets. It also induces no risk of material wear [no abrasion]. A minimum thickness is required for the technical properties of the parts, mainly to have a low frictional coefficient. Depending on the part and its dimensions the aesthetics, color of the part, can be influenced by the thickness of the oxide layer [diffraction of light into the silicon dioxide layer]. Small variations of colors could also happen depending on the direction of the light to the objects.