Silicones

- Silicone is a synthetic polymer which cure, or valcunizes at room temperature into a rubbery material
- Comes in very firm to soft forms

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- It is inert, heat resistant and flexible
- Tin silicone = catalyst is a tin-based chemical
- Platinum silicone = catalyst is a platinum-based chemical
- They can also be named by the manner of combination and valcunization - curing process
- Tin = condensation-cured
- Platinum = addition-cured
- Tin based systems have two different types

One-Part
Typical uses:
- building sealants
- high-consistency rubber compounds
- coating for electronics
- medical bonding adhesives
Advantages:
- easy to use
- low or room temperature cure
Disadvantages:
- can take 24 hours or more to fully cure
Examples include window and bathroom coating. Not suitable for mold making or prosthetics

Two-Part
Typical uses:
- high-speed, high-volume operations such as application of silicone release coatings
- injection molding of liquid silicone rubber
- soft skin adhesives for healthcare applications
Advantages:
- longer shelf life
- high speed cure
- ability to carefully control bath life and cure time by manipulating the formulation
Disadvantages:
- mixing required
- often requires more sophisticated processes and formulating/application expertise

Platinum or Tin
- Both types have unique properties that make them suited to certain applications
- If high temperature then addition cures are typically better
- For economy, general mold making and prototype applications condensation cure would be preferable

Tin
Advantages:
- cost
- resistant to catalyst poising or substrate inhibition - it sets over almost anything
- adhesion
- versatility
Disadvantages:
- it leaches silicone oil over time and becomes brittle
- tin molds can't be used for casting platinum silicone
- need air and moisture to cure

Platinum
Advantages:
- cures without by-products and can be accelerated by heat with no loss of 'library' life
- clear, deep-section cure, no shrinkage
- cures in a vacuum, so good for multipart molds
- textures can be altered with additives to make a fleshier more flexible product
- good adhesion
- some formulations are safe to use directly on the skin
- certain formulations used for medical adhesives or to attach other silicone pieces, some are self-adhesive in their uncured state
Disadvantages:
- potential for catalyst poising and substance inhibition
- catalyst cost can be prohibitive in large amounts

- Silicone can look and feel remarkably like real skin when coloured intrinsically with pigment

- Human skin is actually translucent

- When silicone is coloured internally with pigments and flocking silicone has actual depth just like skin.

- There is no set formula for colouring silicone, although many agree that pigmenting roughly 1% of the total silicone volume is good.

- You want to maintain a slight transluceny with the pigment - not make the piece opaque

- The method the writer learnt from Neill Gorton is marking a mixing stick with a sharpie marker. You add the pigment into the silicone a few drops at a time. Once you've stirred it in let the silicone mostly drain off the stick and if you can just barely see the marker then the amount of pigment is just right.

- If you colour the silicone extrinsically you need a silicone-based colouring system

- You can achieve relatively decent results with a creme foundation but the moment the actor brushes the makeup at all the foundation is going to come straight off

- There are silicone-based air-brush paints and makeup foundations designed for use on silicone appliances which can be used and won't wipe off so easily.

Debreceni, T (2013) Special Makeup Effects for stage and screen. 2^nd edition. Abingdon. Focal Press