Silicone X is a platinum (addition) silicone with Shore A25 hardness, specifically formulated for casting into alginate moulds to obtain flexible, accurate reproductions of human body parts. Its 1:1 mix ratio by weight and volume simplifies the process, and once cured it delivers a tear-resistant rubber with minimal shrinkage, certified safe for skin contact.
Technical specifications
Parameter
Value
Silicone type
Platinum (addition)
Colour
Translucent
Shore Hardness
A25
Mix ratio (weight)
100A : 100B
Mix ratio (volume)
100A : 100B
Working time at 25 °C
30 minutes
Cure time (demould) at 25 °C
3 hours
Viscosity
5,000 cps
Elongation at break
300 %
Tear resistance
100 pli
Shrinkage
≤ 0.1 %
Density
1.20 g/cm³
Skin certification
Skin safe
What it is used for
Silicone X is designed for artists and professionals who need high-fidelity reproductions of human body parts. Its low hardness and high elongation ensure that the finished piece flexes and demoulds without distorting fine detail. The most common applications are:
Reproduction of hands, fingers and stumps for soft prosthetics or special effects
Cloning of intimate body parts for adult-use or artistic products
Face and neck moulds for film and theatre special effects
Casting inside alginate moulds (Alga-Cast Fast) to capture fine skin detail
Artistic and sculptural reproductions of human anatomy
Parts for sex toys and body-contact articles (pigment only with food-grade pigments if internal contact is involved)
How to use it
Prepare the alginate mould: take the impression with Alga-Cast Fast and remove the body part from the mould before the alginate dries out excessively.
Weigh parts A and B: mix 100 parts of component A with 100 parts of component B by weight or volume. The ratio is strictly 1:1.
Mix thoroughly: stir for 2–3 minutes, scraping the sides and bottom of the container carefully to ensure a uniform cure. You have 30 minutes of working time at 25 °C.
Add pigment if needed: at this stage you can incorporate silicone pigments or Key-Pigments FX for colour effects. If the piece will be in contact with the inside of the body, use only food-grade pigments.
Pour into the mould: cast the liquid silicone directly into the alginate mould. Pour in a thin stream to minimise air bubbles.
Cure time: allow to cure at room temperature (25 °C) for a minimum of 3 hours before demoulding.
Demould carefully: the alginate releases easily from the cured silicone. Clean the piece with warm water; it is dishwasher safe.
Warning: risk of cure inhibition
Silicone X is a platinum (addition) silicone. In its liquid state it may be inhibited — that is, remain tacky and fail to cure — if it comes into contact with certain materials: latex, sulphur, sulphur-containing clays, tin (condensation) silicones, freshly cast polyester, epoxy, urethane rubbers or petroleum jelly. Do not apply the liquid silicone directly onto skin or onto untested surfaces. Always mix in clean containers and pour into the alginate mould or a contamination-free mould.
Usage tips
Temperature and cure time
At 25 °C you have 30 minutes to work the mix, and the piece is ready in 3 hours. If the ambient temperature is lower (cold workshop in winter), curing will take longer. Never force the process with excessive heat: above 60 °C in the presence of contaminants the risk of inhibition increases. At lower temperatures both working and cure times extend proportionally.
Pigmentation and colour effects
Silicone X cures translucent, making it a perfect base for achieving realistic skin effects. Add silicone pigments before mixing the two components for a homogeneous distribution. For FX special effects with veins, spots or gradients, Key-Pigments FX offer colours specifically formulated for silicone. Remember: if the piece will be used inside the body, use only food-grade pigments.
Thickening the mix for vertical pours
In some projects you may want to thicken the silicone to reduce flow or for layer-by-layer applications. Thixo Additive makes the mix thixotropic without affecting cure time or the mechanical properties of the finished product. Add it to part A before mixing with part B.
Frequently asked questions
What materials inhibit the cure of a platinum silicone?
Platinum silicones like Silicone X may not cure correctly if they come into contact with: latex, sulphur or sulphur-containing clays, tin (condensation) silicones, freshly cast polyester or epoxy, urethane rubbers, petroleum jelly, and certain metals or unsealed surfaces. If you suspect contamination, always run a small test before pouring the full batch.
Can I use this silicone directly on skin?
Silicone X is certified as safe for dermal contact once cured. However, you must not apply liquid silicone directly onto skin: in its uncured state there is a risk of inhibition and adhesion. The correct process is to first take an impression using a body-grade alginate such as Alga-Cast Fast and then cast Silicone X inside the resulting mould.
Can I use any mould to cast this silicone?
Silicone X is optimised for casting into alginate moulds, which are inert towards platinum silicone. If you use other mould materials (plaster, resin, etc.), make sure they are fully cured and sealed, and that they contain no contaminants that could inhibit the cure. Always run a compatibility test.
How can I colour the silicone to achieve a realistic skin tone?
Silicone X cures translucent, which makes pigmentation straightforward. Add silicone pigments or Key-Pigments FX to part A before mixing with part B for a uniform distribution. If the piece will come into contact with the inside of the human body, use exclusively food-grade pigments.
How long do I have to work the mix before it starts to cure?
At 25 °C you have 30 minutes of working time from when you mix components A and B. After that time viscosity increases rapidly and the silicone stops flowing correctly. Safe demoulding occurs at 3 hours at the same temperature. Lower temperatures extend both times.
Can a tin silicone be used for the moulds and Silicone X cast inside?
No. Platinum silicone does not cure over tin (condensation) silicones: it would be inhibited and remain tacky. If you need a flexible silicone mould to cast Silicone X into, always use a compatible platinum silicone and make sure to apply a release agent between the two silicones.
Is it suitable for making intimate-use articles?
Cured Silicone X is certified as safe for dermal contact. For intimate-use articles involving internal contact, it is essential to pigment only with food-grade pigments. Always check the regulations in force in your country regarding the sale of such products.
How do you clean and maintain a piece made with this silicone?
Silicone X pieces are easy to clean with warm water and mild soap. The material is dishwasher safe, which makes hygienisation straightforward for repeated use. Avoid contact with aggressive solvents or sulphur-containing materials, which could degrade the surface over time.
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