Samsil Semi Clear 25

Samsil Semi Clear 25 – RTV-2 Silicone Rubber, Shore A 23-27

Samsil Semi Clear 25 is a 2-component addition-cure (poly-addition) silicone that cures at room temperature. It is a very robust and easy-to-use 1:1 system based on a platinum catalyst. This silicone combines high tear strength with relatively good transparency – not crystal clear, but considerably more transparent than most standard silicones.

Specific properties

• Low viscosity, good deaeration
• High tear and tensile strength
• Non-bleeding
• Higher transparency than most silicones

Compatible additives

• Thixo – to thicken the consistency
• Retarder – to extend working and cure time
• Accelerator – to shorten working and cure time
• Colourant – to add colour

Technical Characteristics

Basic specifications:

• Type: 2-component platinum-cure silicone (poly-addition)
• Mix ratio: A:B = 100:100 (1:1 by weight)
• Pot life: 30 minutes at 25 °C
• Cure time: 3-5 hours at 25 °C
• Full strength: 1 day at 25 °C
• Appearance: colourless, transparent
• Density: 1.03 g/cm³ at 25 °C
• Viscosity: 12,000 ± 500 mPa·s at 25 °C
• Hardness (DIN 53505): Shore A 23-27
• Tear strength: 5 kg/cm
• Tensile strength: 12 kg/cm²
• Elongation at break: 500%
• Shrinkage: <0.1%

Processing instructions:

1. Mix Part A and Part B thoroughly in a 100:100 ratio (1:1 by weight), by hand or by machine
2. Stir slowly in a figure-of-eight motion to avoid trapping air
3. Use the mixture within the 30-minute pot life
4. Do not demould until fully cured (3-5 hours at 25 °C)
5. Curing can be accelerated with heat – every 10 °C rise in temperature roughly halves the time

Storage & Use

• Store in a dry place between 5 and 25 °C, in tightly closed packaging and protected from direct sunlight. Shelf life at least 1 year when stored correctly.
• Addition-cure silicones can be contaminated by materials such as sulphur and tin salts. Avoid contact with these substances. See our website for a comprehensive list of potential inhibitors.
• Working and cure times depend strongly on temperature. Higher temperatures shorten the working time.

Important Warning: Inhibition of Addition-Cure Silicones

Please note: this is an addition-cure (platinum-cure) silicone. Addition-cure silicones can be poisoned by sulphur, nitrogen, amine compounds and metal salts. If you are not sure whether the products you use (including gloves, spatulas and cups) contain these substances, carry out a small test first.

Note: do not deviate from the mix ratio (1:1), as this will change the properties of the silicone.

The results stated are typical indications, not specifications. The customer must test the product to determine whether it is suitable for the intended purpose.