multi-piece

You will have to consider where you want the pieces to overlap before you cut the sculpture apart.

There is certainly nothing wrong with that approach, it's just extra work.

If you are creating a heavily textured make up, you can use another Dick smith idea - "blenders". These are small prosthetics used to tie together appliances that have shrunk, are misaligned, or have bad edges. Very small gaps between pieces can be concealed with Ridge Fillers (PAX & Cab-O-Sil mixed is a common one).

Single piece appliances give accceptable results with the casting materials we have today.

Blue, Are you asking about a multi piece appliance, or a multi piece mold to make one appliance?

Multipiece molds are used when undercuts would be a problem, such as when you need to create a mold of an entire 3D object.

Multi piece appliances are used to avoid the hassle of properly aligning a one piece prosthetic, or when the features being altered are far enough away that a one piece prosthetic make sno sense (a bullet hole in the forehead and a wart on the chin), or simply when the make up artist prefers it.

Making mold walls, good molds, blending edges on prosthetics, casting, and prosthetic application are all complicated enough subjects that we'd have a hard time doing them justice trying to describe them well enough in a forum like this. Several good books have been written. I highly recommend Lee Baygan's book 3D Make Up for clear photos and directions.

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If your foam is shrinking as much as 30% (the way R & D commonly did) then you'd better change foams. I've never had more than minimal shrinkage.

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Originally posted by morpherguy:
Overlapping prosthetics can be done in a number of ways. I use the Dick Smith method. What you do is sculpt your design on top of a plaster casting of the actors face that has been coated with a dental seperator. I use Alcote. You let the seperator dry before you apply the clay. AFter you are done sculpting, you will use a pallet knife and cut the clay into the different pieces that you want to make, example: forehead, nose, cheeks etc.. Just slice right through the clay, make sure the knife makes contact with the plaster cast. After you do this, put the plaster cast into a container of water and let it soak for around 24 hours. What will happen is this; The seperator will dissolve and allow the clay to be removed with no problem at all. You will be able to simply lift the clay sections off of the plaster life cast. Before you do any of this you will want to prepare a set of positives for each piece to be transferred to. Example. You will have to make a forehead positive so that when you remove the forehead sculpture from the plaster cast of the actors face you will have a mold to re-attach it to so you can make a negative over it. Once you transfer the clay to the positive you can fix the edges and feather them into the positive. It is important that you make the plaster positive of the actors face out of plaster and not Ultracal-30 because when you put it in the water it has to be able to absorb water so that the seperator will dissolve. Ultracal is not very pourous and will not work well with this technique.
what plaster can i use?

You will have to consider where you want the pieces to overlap before you cut the sculpture apart.

This process is a little bit more complicated than I have had time to write about.

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