How to make Prosthetics

How to make Prosthetics

The process of creating a prosthetic appliance often begins with lifecasting. This is the procedure of taking the mould of a body part (often the face) to use as a base for sculpting the prosthetic onto. Lifecast moulds are made from prosthetic alginate, or skin-safe silicone rubber. At Mouldlife | PS, we stock everything you need for lifecasting- our Face and Body Cast silicone is the most favoured option (due to the ability to get numerous casts from it and due to it’s ease of use).

The lifecasting silicone (Face and Body Cast) is a two-part platinum system. Mixing parts A and B to a ratio of 1:1 will gives you a 5-10 minute working time, dependant on room temperature. It’s viscosity allows you to do a controlled lifecast without having to worry about excess material dripping everywhere. It also releases hair without any need of folic agents or oils. For those people who are on a tighter budget, or only need the lifecast to be for one cast, alginate is a great cheaper option. We provide it in 500gm bags, and two bags should be sufficient for a full face and neck. For backing the alginate or lifecasting silicone, plaster bandage (Gypsona) or Mod Roc is used. The plaster bandage that we stock is of a very high grade and sets very fast, enabling the lifecast to be reduced in time. Mod Roc is a cheaper reduced-grade plaster bandage and therefore takes a little longer to set. When lifecasting anyone’s head it is always advisable there are at least two people to do the cast, and at least one of them should be experienced with the process.

From this lifecast we can create a positive cast (core) using plaster, fibre-glass, epoxy, or urethane. The form of the prosthetic is sculpted with wet clay or sculpting wax (Chevant or Monster clay) on top of the positive cast (core). The edges of the sculpt should be made as thin as possible, for the clay or wax is a stand-in for what will eventually be the prosthetic piece. Along the edges of the mould, “keys” or “mould points” are sculpted into the lifecast, to make sure that the two pieces of the mould will fit together correctly.

Once sculpting is completed, a second mould is made. This gives two or more pieces of a mould, a positive core along with one or more mould pieces- the negatives of your sculpt. You can choose to mould the second part in many different ways (e.g. block moulds or jacket moulds) depending on what material you wish your prosthetic to be. After the mould is completely finished and prepped with bolt-holes, it needs to be carefully opened and cleaned from sculpting clay or wax. Now clean, the mould can be prepped with bleed holes and pour tubes (again depending on mould type). Prosthetic material can then be cast into the mould cavity. The prosthetic material can be foam latex (Monster makers foam latex system), gelatin, or silicone (Pro-Gel 10 system). Always ensure you use the appropriate release agents.

If the prosthetic is to be cast in Pro-Gel 10 silicone it is best to encapsulate the silicone in cap plastic. Cap plastic will give you the finest of edges. It is sprayed into the mould either through an air-brush or spray gun, though it can be painted if a spraying system isn’t available. Pro-Gel 10 is a two-part platinum silicone system that can be softened with an additional third part (deadener). The one to one ratio of the Pro-Gel 10, mixed together with multiple variants of deadener, will give you the most realistic effects for replicating skin. The Pro-Gel 10 system is unique to Mouldlife | PS, and has been engineered to bond to cap-plastic like no other material in its field. It is runnier than other prosthetic silicone systems on the market, allowing it to travel into the mould at a greater speed (thus reducing the probability of unusable pieces from the moulds). It also has a very fast de-mould time. The prosthetic is cured within the multiple part mould, creating the beginning of a makeup effect.

Having taken your successful prosthetic piece from the mould, it is now ready to apply (prosthetics are often pre-painted- see our painting rubber guide for more info). When applying the prosthetic it is important to remove any grease from both the piece and the skin you are applying it to. Not doing so will potentially cause problems with adhering it to skin. The prosthetic is glued to the skin using adheisives (Telesis 5, Beta Bond). In areas where the prosthetic could lift it is often a good ideas to use a sealer (Green Marble) on the skin prior to sticking the prosthetic on.

Once the pieces are all stuck down and edges are blended onto the skin, it is time to colour up the prosthetic. To colour prosthetics a multitude of mediums are available, depending on what the prosthetic is made from. For foam latex, Pax paint, grease and Skin Illustrator are used. For gelatin and silicone it is most advisable to paint with an alcohol-based paint system (Skin illustrator). This is because the paint doesn’t move and it gives you the most realistic effects. You can use a brush or air-brush depending on desired effect. One of the hardest parts of prosthetic make-up is keeping the edges looking flawless through the entire day. The better the application and care from the artist, the easier this gets.

If you have any technical questions please contact us or call 01638 750 679 (international clients: +44 01638 750 679). At Mouldlife | PS, we have many years of experience. We also have several members of staff current working within the industry who would be more than happy to assist with your queries.

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