and very, very hot.
The workers wear thick asbestos clothes when they approach the vessel or the oven and then tear it off as they walk away.
There is this constant dance of dressing and undressing that cycles every 30 seconds or so.
A large intricate cast piece takes days of work to create the wax model, then to create the mold and bake it to harden it and burn off the wax.
The mold has to be kept at high temperature so that the molten metal is helped to stay liquid while it penetrates to all the fine edges.
The intent is that the sprues are the last portion to solidify and provide liquid metal to the casting to prevent porosity and blemishes there.
When and how to pour these complex pieces with several sprues and casting thicknesses is very much an art and the person in charge of the pour is the absolute boss.
(I used to do small item casting as a hobby and that was difficult and hot enough.)