Silicone is a synthetic polymer, derived from silicon metal.  The nature of its origin gives it a number of significant advantages over conventional rubber polymers.  Silicone is available in the form of rubbers, greases, and fluids.

No.  Silicone is not affected by extremes of weather – hot, cold, dry, wet, or humid.  It also has excellent resistance to UV and ozone degradation.

Silicone is more expensive than most rubber types because it is a speciality high performance polymer with outstanding qualities.  It is made in relatively low quantities and requires expensive and complicated primary manufacturing facilities.

Silicone can be supplied in a very wide range of colours, including fluorescents, metallics, and even those that change colour with heat!

Broadly speaking, the service temperature range of silicone is within the region of -110C to +315C.

Silicone is not normally considered as volatile.  However, it can lose a fraction of its weight as the temperature rises.

By the addition of carefully selected chemicals, silicone can become a good conductor of heat.

Both!  Silicone is an exceptional electrical insulator.  It is the material of choice in fire survival cables as even the ash is non conductive.  However, silicones can be modified with certain special fillers to become very good conductors of electricity.  These products can then be used for seals for use in shielding applications.

Silicone is not inherently flame retardant but can be modified to give good flame retardant properties.  Indeed, because of its excellent biomedical properties, silicone is widely used in the fire protective clothing industry.

Parts made from silicone are not adversely affected by immersion in fresh, or seawater.

Silicone is suitable for use in most clean room environments.  The polymer itself does not support microbiological growth.

Silicone is very permeable to most gases and as such would not be ideal for use in applications involving rapid decompression.

Products made from silicone should not be used in high traffic applications because even the best high strength compounds have a relatively modest resistance to abrasion wear.

Products made silicone are very difficult to paint. Special surface treatments can help but in general silicones resist paint application.

Silicone rubber compounds can in general be processed on conventional rubber processing machinery.

The effective shelf life of silicone rubber compounds is dependant largely on what is required from the compound in processing terms.  The material tends to stiffen with age but this can be overcome by freshening on a two-roll mill. In general terms most compounds have a declared shelf life of at least 6 months.

Silicone compounds should be stored in a dry environment away from direct sunlight and heat, and at a temperature of less than 30C.

Silicone rubber is a thermoset so once the material has cross-linked it cannot be practically de polymerised by heat as in the case of a thermoplastic.

Room Temperature Vulcanisation.  RTV means that the silicone in question is capable of curing at room temperature.  These materials tend to be supplied in a liquid or semi liquid form.

High Temperature Vulcanisation.   HTV means that the silicone in question is cured with the application of heat.  These materials tend to be supplied in a thick putty type form and thus are processed used moulds and extruders.

Some silicones are described as addition cured because the cure mechanism is a catalyst reaction between the component ingredients within the compound.  These components need to be added together for the compound to cure hence the term addition.  Addition cure compounds can be supplied as one, two or three component systems.

The time taken to cure a silicone compound depends on a number of factors.  These include temperature, section and cure mechanism.  In practice a typical cure time for a compression moulded part is in the region of 5 minutes at 180C.

The terms curing and vulcanisation essentially describe the same thing - the transformation of the polymer into a cross-linked rubber.

The cure time can be accelerated to a certain extent by a combination of the following - higher temperatures, mould design, processing method, and changing from a peroxide cured compound to a addition cured compound.

There is a possibility that certain compounds (usually those used for extrusion purposes) can evolve very low quantities of PCB''s.  These are derived from the peroxide used to cross-link the silicone.  It is therefore wise to ensure that adequate ventilation and extraction is provided in the areas where such compound is being processed.

Silicone liquids can be thickened to a certain extent by the addition of silicas.

Silicone polymers can be dispersed in solvents to decrease their viscosity.
Due to environmental and health and safety concerns however, this practice is seldom carried out today.

Silicone rubbers can be bonded to a range of substrates including common metals and plastics with the use of special primers and surface preparation techniques. 

Conventional silicone rubber is not suitable in environments where it comes into contact with oils fuels and solvents.  Fluorosilicone however, performs excellently under such conditions.  Silicone rubbers in general also have poor resistance to steam and super heated water. 

Silicone rubber cured or un-cured is not considered as hazardous waste and therefore can be disposed of in accordance with the local regulations regarding waste disposal.

Silicone rubber has been used for long-term medical implantation. An example is finger joints. The recent bad publicity about breast implants has meant that the major silicone manufacturers do not recommend their products be used for more than 28 days.

Silicone can be made to change colour with temperature by the addition of special thermachromic pigments.

Silicone is considered to be a very safe polymer with virtually no toxic effects in most environments.  Also, as silicone is not considered as hazardous waste it can be disposed of in accordance with the local regulations regarding waste disposal.

Silicone rubber is among a number of rubber types that can be used in contact with food. It has the advantage of being a low taint non-toxic material.

Specific grades of silicone rubber are used widely in the production of baby bottle teats due to their cleanliness aesthetic appearance and low extractable content.

The maximum size of a silicone moulding is theoretically limited by the size and capacity of the processing and curing equipment.