Silicone RTV-2
Grade
also PDMS, LSR
RTV-2 = rTV-2 / Cast PDMS
Pick for prototyping molds, microfluidic PDMS chips, potting and encapsulation where no heated press is available.
Values for the RTV-2 condition
Other Silicone grades and fills
Silicone is listed in 15 conditions; see the grade overview at Silicone.
Compare all 15 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Sponge/Foam | Pick for low-closure-force weather seals, cushioning and insulation in enclosures and ovens. | — | 2 | 150 | 25 Shore A |
Electrically conductive silicone | Pick for EMI gaskets, grounding pads and ESD-safe seals combining shielding with environmental sealing. | — | 3 | 120 | 20 Shore D |
Thermally conductive (alumina / boron nitride filled) silicone | Pick for thermal interface pads, gap fillers and potting where heat must be moved but electrical isolation kept. | — | 3 | 120 | 18 Shore D |
RTV-2This page RTV-2 / Cast PDMS | Pick for prototyping molds, microfluidic PDMS chips, potting and encapsulation where no heated press is available. | — | 6 | 350 | 8 Shore D |
soft grade | Pick for soft-touch skins, low-force seals, membranes and conformal cushions. | — | 7 | 650 | 6 Shore D |
heat-stabilized (iron oxide / rare-earth) silicone, 250–300 °C capable | Pick for oven gaskets, exhaust/turbo seals, ironing and heater components where continuous service exceeds 200 °C. | — | 7 | 350 | 15 Shore D |
flame-retardant silicone (UL 94 V-0) | Pick for rail, EV battery and appliance parts needing UL 94 V-0 with low smoke and halogen-free formulation. | — | 7 | 350 | 16 Shore D |
soft-medium grade | Pick for baby-care parts, low-compression-force gaskets and flexible tubing. | — | 8 | 550 | 9 Shore D |
HCR/HTV | Pick for extruded profiles, tubing, calendered sheet and low-volume compression-molded gaskets. | — | 8 | 400 | 15 Shore D |
Fluorosilicone, fuel and oil resistant | Pick when silicone-level cold flexibility is needed together with resistance to fuels, hydrocarbon oils and solvents. | — | 8 | 250 | 16 Shore D |
general purpose grade | Pick as the default all-round hardness for O-rings, keypads and static seals. | — | 9 | 450 | 12 Shore D |
Liquid silicone rubber, 2-part platinum cure, injection molded | Pick for high-volume automated injection molding of thin, flash-free, dimensionally precise parts. | — | 9 | 550 | 12 Shore D |
medium-hard grade | Pick for dynamic seals, grommets and parts needing better set resistance and extrusion resistance. | — | 9 | 400 | 15 Shore D |
extra-hard grade | Pick for rollers, back-up rings and parts resisting extrusion under high clamp loads. | — | 9 | 220 | 30 Shore D |
hard grade | Pick for high-pressure gaskets, valve seats and stiff overmolds. | — | 10 | 320 | 22 Shore D |
What is Silicone RTV-2?
Silicone RTV-2 is Silicone in the RTV-2 grade — pick for prototyping molds, microfluidic PDMS chips, potting and encapsulation where no heated press is available. Silicone RTV-2 has a tensile strength of 6 MPa (0.798 ksi), weaker than 82% of polymer grades. Elongation at break is 350% and the elastic modulus is 0 GPa (2.61×10⁻⁴ Msi). Silicone RTV-2 has a density of 1.15 g/cm³ (0.0415 lb/in³), lighter than 57% of polymer grades. Its glass-transition temperature is -125°C (-193 °F).
Advantages
- Forms and bends easily — 95/100, better than 99% of polymer grades
- Good UV / weathering resistance — 97/100, better than 98% of polymer grades
- Polishes to a fine finish — 85/100, better than 92% of polymer grades
- Low, predictable mold shrinkage — 0.3%, better than 90% of polymer grades
- High service temperature — 180°C (356 °F), better than 85% of polymer grades
Limitations
- Difficult to machine — 18/100, worse than 98% of polymer grades
- Low stiffness — 0 GPa (2.61×10⁻⁴ Msi), worse than 96% of polymer grades
- Difficult to weld — 15/100, worse than 78% of polymer grades
Silicone RTV-2 properties
Typical room-temperature values for Silicone RTV-2; 17 are specific to this condition. Other listed values are Silicone reference data and may not represent this condition. Bars are the position among polymer grades.
Physical5
Silicone RTV-2 has a density of 1.15 g/cm³ (0.0415 lb/in³), lighter than 57% of polymer grades. Its glass-transition temperature is -125°C (-193 °F).
Mechanical9
Silicone RTV-2 has a tensile strength of 6 MPa (0.798 ksi), weaker than 82% of polymer grades. Elongation at break is 350% and the elastic modulus is 0 GPa (2.61×10⁻⁴ Msi).
Thermal8
Silicone RTV-2 is rated for continuous service to 180°C (356 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 56% of polymer grades. Thermal expansion is 270 µm/m·K (150 µin/in·°F).
Electrical7
Silicone RTV-2 is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 74% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of Silicone RTV-2 takes about 110 MJ of energy and emits 6.5 kg of CO₂ — more than 64% of polymer grades. Typical recycled content is 0%.
Manufacturability7
Silicone RTV-2's machinability is poor (18/100, worse than 98% of polymer grades); weldability poor (15/100); formability excellent (95/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Silicone RTV-2
Is Silicone easy to machine?
Cured silicone is not conventionally machinable — use die cutting, waterjet, laser (with fume control) or cryogenic deflashing; sharp new blades and water lubrication prevent tearing.
Can Silicone be welded?
No thermal welding; join by uncured silicone adhesive, self-bonding primers, RTV, or oxygen-plasma bonding for PDMS microfluidics; secondary overmolding onto cured silicone requires primer.
Can Silicone be formed, bent or molded?
LSR: cold runner, 165–210 °C mold, 15–60 s cure, allow 2–3 % shrink and vacuum-vented tools; HCR: compression/transfer or extrusion + hot-air/steam cure; post-cure 200 °C/4 h to remove volatiles for medical/food use.
What surface finishes work on Silicone?
Surface finish is fully set by the mold (mirror EDM or texture); paints do not adhere without silicone-specific primer — use plasma/corona treatment, parylene or silicone inks; talc-free anti-block coatings for tack reduction.
Silicone chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| fumed silica (reinforcing filler)surface-treated, sets modulus and tear strength | 15 – 35 | 25 |
| hydride crosslinker (Si-H siloxane)addition-cure systems | 0.5 – 3 | 1.5 |
| platinum catalyst (Karstedt)peroxide (DCBP/DBPMH) used instead in HCR peroxide cure | 2×10⁻⁴ – 0 | 5×10⁻⁴ |
| extending filler / pigment / heat stabile.g. ground quartz, Fe2O3, Ce compounds | 0 – 15 | 5 |
| polydimethylsiloxane (PDMS) base polymermay contain vinyl-methyl and phenyl or trifluoropropyl substitution | ≥ 55 (balance) | — |
Silicone RTV-2 — frequently asked
What is Silicone RTV-2 used for?
Silicone RTV-2 is typically used for O-rings and moulded gaskets, medical tubing and implant seals, keypads and button mats, baby bottle nipples and food-contact seals, electronic potting and encapsulation and high-temperature oven and appliance seals. In short: biocompatible soft silicone.
What is the tensile strength of Silicone RTV-2?
Silicone RTV-2 has a typical tensile strength of 6 MPa (0.798 ksi) — weaker than 82% of polymer grades. Strength varies by condition: see the 15 listed tempers.
Is Silicone RTV-2 easy to machine?
Not especially — machinability is rated poor (18/100, worse than 98% of polymer grades). Cured silicone is not conventionally machinable — use die cutting, waterjet, laser (with fume control) or cryogenic deflashing; sharp new blades and water lubrication prevent tearing.
Can Silicone RTV-2 be welded?
Not readily — weldability is rated poor (15/100). No thermal welding; join by uncured silicone adhesive, self-bonding primers, RTV, or oxygen-plasma bonding for PDMS microfluidics; secondary overmolding onto cured silicone requires primer.
What surface finishes work on Silicone RTV-2?
Surface finish is fully set by the mold (mirror EDM or texture); paints do not adhere without silicone-specific primer — use plasma/corona treatment, parylene or silicone inks; talc-free anti-block coatings for tack reduction.
Can Silicone RTV-2 be formed, bent or molded?
LSR: cold runner, 165–210 °C mold, 15–60 s cure, allow 2–3 % shrink and vacuum-vented tools; HCR: compression/transfer or extrusion + hot-air/steam cure; post-cure 200 °C/4 h to remove volatiles for medical/food use.
What is the maximum service temperature of Silicone RTV-2?
Silicone RTV-2 is rated for continuous use to about 180°C (356 °F), and briefly to 250°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Silicone RTV-2?
Yes — Silicone RTV-2 is available for injection molding; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D2000 — Classification System for Rubber Products (VMQ/FVMQ) — ASTM (2023)
- ASTM D412 / D624 / D395 / D2240 — tensile, tear, compression set, durometer — ASTM (2022)
- SILASTIC / Dow LSR and HCR product datasheets — Dow (2023)
- ELASTOSIL LR / R silicone rubber datasheets — Wacker Chemie (2023)
- Silopren LSR and thermally conductive silicone data — Momentive (2022)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics/Elastomers — ASM International (1988)
- CAMPUS / UL Prospector elastomer entries — UL / CAMPUS (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.