Silicone Addition Colourless 5 – Very Soft Platinum Silicone for Masks & Flexible Moulds

Premium Very Soft Silicone for Professional Flexible Moulds

Silicone Addition Colourless 5 is a 2-component, platinum-cure (addition-cure) casting silicone that cures at room temperature to a transparent, very soft rubber (Shore A 5) with a slight yellowish tint and 500% elongation. The silicone flows well (approx. 2,500 cSt), is temperature resistant from -40 °C to +280 °C and is particularly suited to highly detailed, flexible moulds of delicate masters and to skin-friendly applications such as masks, props and body casting. Easy 1:1 mixing ratio and adjustable hardness by mixing with the Shore A 50 variant.

Key Benefits

• Exceptional softness: Shore A 5 for maximum flexibility and comfort in skin-contact applications
• High elongation: 500% elongation with 2.5 N/mm² tensile strength and 8 N/mm tear strength for flexible moulds that demould easily
• Good flow and self-de-airing: approx. 2,500 cSt viscosity for good detail reproduction; for a completely bubble-free result we recommend vacuum degassing the mixture after mixing
• Platinum-cure technology: Very low shrinkage (<0.1%), fast demoulding (approx. 2 hours at 20 °C), temperature resistant from -40 °C to +280 °C
• Adjustable hardness: Mixable with Silicone Addition Colourless 50 for any desired hardness between Shore A 5 and 50
• Can be coloured: Transparent with a slight yellowish tint, easy to colour with silicone pigment

Typical Applications

• Masks and prosthetics for SFX, film, theatre and cosplay – skin-friendly and comfortable
• Props and flexible decorative elements for the entertainment industry
• Highly detailed candle moulds for artisan candle makers
• Body casting and lifelike impressions for art and medical simulation
• Soft, flexible soap moulds for artisan soap production
• Podiatry applications and medical models where softness is essential

Processing instructions:

1. Carefully mix components A and B in a 100:100 ratio (1:1 by weight) by hand or mechanically
2. Stir slowly in a figure-of-eight motion to trap as little air as possible
3. Vacuum degas the mixture after mixing; this is the best way to prevent air bubbles
4. Process the mixture within the 30-minute pot life (at 20 °C)
5. Only demould once fully cured: approx. 2 hours at 20 °C
6. The best properties are only achieved by post-curing: place the mould in an oven at 140 °C for 1 hour

Pot life and demoulding time depend strongly on temperature: at higher temperatures both the working time and the demoulding time become shorter.

Customisation options:

• Adjust hardness: Mix with Silicone Addition Colourless 50 for any desired hardness between Shore A 5 and 50. Always mix both the A and the B component of both hardnesses. Example: for Shore A 18.5, mix 70% Shore 5 (35 g A + 35 g B) with 30% Shore 50 (15 g A + 15 g B)
• 
• Reduce hardness: Add silicone oil (note: the oil does not crosslink and slowly sweats out over time)
• Thicken for spreading: Add Silicone Thixo A or fumed silica (not Silicone Thixo C)
• Colouring: Use silicone pigment for intense colours

Packaging and shelf life: Supplied as a 1:1 set. Stored in the closed packaging, cool and frost-free, the shelf life is at least 1 year.

Silicones and More supplies high-quality silicones for professional mould making, SFX, body casting and flexible mould applications.

Important Warning: Inhibition in Addition-Cure Silicones

Note: This is an addition-cure silicone (platinum-cure). These silicones can be inhibited by sulphur, nitrogen, amino compounds and metal salts. If you are unsure whether the products you are using (including gloves, spatulas and cups) contain these ingredients, please do a small test first. These substances are found in many latex gloves, some plasticines, paints and adhesives, condensation-cure silicones, 1-component silicone sealants, natural rubbers and 3D printing materials (especially stereolithography). If you still wish to use these, you will need to apply a protective layer of polyvinyl alcohol (PVA).

Professional Support

Our technical specialists advise on material selection, hardness adjustments, processing techniques and optimal results for your specific flexible mould or mask application. Contact us for technical data sheets, processing guidelines or advice on preventing inhibition in addition-cure silicones.