How are individual cores created for individual prosthetics?

[Leatherface75]

Hello, new person here.

I was hoping could point me in the right direction here.

My question deals with the smaller, broken down core positives that are used to finish multi-piece appliance sculpts after they're "floated" off a main headcast. The pictures and videos I've seen show these very clean-cut, ready to mold portions of specific parts of the face.

I know that many use 3d printed cores nowadays, but how these created the old school way? Any help would be appreciated.

Examples:

 

[udog]

As for the core sections one way is making a life cast of the complete head or face. Once you have that positive you make smaller silicone molds of the areas you want to break down, with their flanges and reference keys.
Then you can pull castings of those section molds and you can sculpt on them and mold your prosthetics individually.
Or you can sculpt on the original full lifecast, cut the sections you want and float the clay off and then place it on your previously section casted mold cores, finish your edges there and mold.
To float off the clay from the complete lifecast you must previously seal it (if plaster) and release with dish soap for example, several layers. After you have sculpted and made your cuts,to get the clay to separate you will have to put the head it in a bucket of water let it sit there and the clay should separate.

 

[Mr Mold Maker]

Typically you’d make waste molds or “snap” molds as some folks call them, off of the headcast. Alginate or thin silicone. You only need one copy out of this mold hence it being a “waste mold.” Cast a copy in stone or resin and then you can sculpt your flange, keys, do any corrections needed to remove undercuts etc. Then you’d mold that, and produce your final core from that mold.


Stan Winston School has a great video on the whole process. Highly recommend their site. They have fantastic videos.

Here is a snippet from it showing the waste molding step.