Bluesil RTV 3720 B SC (5 kg)
BLUESIL RTV 3720 B SC (5 kg) — Slow-cure catalyst for casting applications. 60-minute pot life.
BLUESIL RTV 3720 B SC — light blue slow-cure catalyst for casting applications and manual mixing.
5 kg bucket. Pot life: 60 min, demolding time: 150 min. For larger molds and manual application. Mix 1:1 with Base A. Shipped from our Swiss warehouse.
Internal reference:
40-2309B.KN.K005
HS code:
39100000
BLUESIL RTV 3720 A&B – Vacuum-bag silicone for composite manufacturing
BLUESIL RTV 3720 A&B is an addition-curing two-component silicone rubber designed for a very specific niche: the production of reusable silicone films ("vacuum bags") for composite molds in vacuum resin infusion technology (VAP, RTM-Light, infusion). The silicone film is applied directly to the composite mold and replaces traditional disposable vacuum bags made of nylon film—this saves material and time and enables precise contact edge geometries.
The product is characterized by low viscosity with slightly thixotropic behavior —meaning it can be easily applied via a spray nozzle but adheres to the mold surface even on vertical sections. The 1:1 mixing ratio is suitable for standard dispensing systems. The final properties are excellent: Shore A 20, tensile strength 4 MPa, elongation at break 500%, tear strength 15 kN/m.
What's in this container?
Catalyst B SC (Slow Cure) 5 kg. Slow-curing version for casting applications: 60-minute working time, 150-minute demolding time. For manual mixing and casting applications.
Two versions: Standard (fast) vs. SC (slow-cure)
| Version | processing time | demolding | Application |
|---|---|---|---|
| RTV 3720 A&B (Standard) | 3 min | 15 min | Spray application |
| RTV 3720 SC A&B (Slow Cure) | 25 min | 90 min | Casting application, manual processing |
Both versions have identical end properties—the choice depends on the application method.
Typical applications
- Reusable vacuum bags for vacuum-assisted resin transfer molding (VARTM), light-RTM, and infusion processes
- Flexible silicone seals in composite form
- Special molds with complex undercuts that cannot be produced using a casting process
Available additives
- Cross-linking retarders for extending the working time (both versions)
- Networking accelerator for shortening (SC version only)
- Thixotropic additive for adjusting flow properties (SC only)
- Silicone adhesive for repairing damaged silicone films
- Silicone paste for protecting sharp parts
Specifications (applies to both versions)
| Shore A | 20 |
| tensile strength | 4 MPa |
| elongation at break | 500% |
| Tear resistance | 15 kN/m |
| Linear shrinkage | < 0,2 % |
| Viscosity A / B | 40,000 / 40,000 mPa·s |
| Color based on the mixture | light blue |
Inhibition Warning (Addition-RTV)
Platinum-catalyzed silicones are inhibited in trace amounts by: sulfur-containing rubbers, tin-catalyzed RTV, tin-stabilized PVC, and amine-cured epoxies. If in doubt, conduct a preliminary test at the test site.
BLUESIL RTV 3720 is supplied by SILITECH AG with technical support, a batch certificate, and shipping from our Swiss warehouse within 24 hours.
Technische Daten zu Bluesil RTV 3720 B SC (5 kg)
| product information | |
|---|---|
| manufacturer | Elkem Silicones |
| brand | Bluesil |
| container | 5 kg |
| network type | Addition (Platinum) |
| Number of components | 2K (two-component) |
| mixing ratio | 1:1 |
| Additional features | |
|---|---|
| UV resistance | No |
| Areas of application | |
|---|---|
| Main application | Formenbau, Prototyping |
| Physical properties | |
|---|---|
| Viskosität unvernetzt (mPa·s) | 30 |
| Paint cured | blue |
| Self-leveling | Yes |
| consistency | Flowable |
| curing values | |
|---|---|
| Pot life (min) | 3 |
| Entformzeit (min) | 15 |
| Mechanical properties | |
|---|---|
| Tensile strength (MPa) | 4 |
| Elongation at break (%) | 500 |
| Reißfestigkeit (N/mm) | 15 |
| Electrical Properties | |
|---|---|
| Electrical insulation | No |
| product approvals | |
|---|---|
| food contact | No |
| Suitable for medical use | No |
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Frequently Asked Questions About BLUESIL RTV 3720 B SC
Answers about the Slow-Cure catalyst.
In vacuum resin infusion (VARTM / infusion), fiberglass or carbon fiber fabric is placed in a mold, an airtight bag (vacuum bag) is stretched over it, and liquid resin is drawn through the fabric under vacuum. Traditionally, vacuum bags are made of disposable nylon film. Silicone vacuum bags made of RTV 3720 are reusable: they are vulcanized directly onto the mold and last for over 100–500 cycles.
RTV 3720 A&B Standard (fast-cure): for spray applicators with static mixers. The extremely short pot life does not allow for manual mixing. RTV 3720 SC A&B (slow-cure): for casting applications and manual mixing. A 60-minute working time is sufficient for large molds.
When installed correctly (Shore A 20, high tear strength of 15 kN/m) and with moderate resin aggressiveness, 100–500 production cycles are typical. Damage can be repaired using Elkem silicone adhesive—which is usually faster than a complete replacement.
Yes. Its excellent mechanical properties (elongation 500%, tear strength 15 kN/m) and low Shore hardness of 20 make the product suitable for flexible seals, glove molds, and silicone film impressions as well. However, its primary application remains the composite vacuum bag—that is what the formulation was developed for.
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product specifications
| product information | |
|---|---|
| manufacturer | Elkem Silicones |
| brand | Bluesil |
| container | 5 kg |
| network type | Addition (Platinum) |
| Number of components | 2K (two-component) |
| mixing ratio | 1:1 |
| Additional features | |
|---|---|
| UV resistance | No |
| Areas of application | |
|---|---|
| Main application | Mold making or Prototyping |
| Physical properties | |
|---|---|
| Viskosität unvernetzt (mPa·s) | 30 |
| Paint cured | blue |
| Self-leveling | Yes |
| consistency | Flowable |
| curing values | |
|---|---|
| Pot life (min) | 3 |
| Entformzeit (min) | 15 |
| Mechanical properties | |
|---|---|
| Tensile strength (MPa) | 4 |
| Elongation at break (%) | 500 |
| Reißfestigkeit (N/mm) | 15 |
| Electrical Properties | |
|---|---|
| Electrical insulation | No |
| product approvals | |
|---|---|
| food contact | No |
| Suitable for medical use | No |
| keywords | |
|---|---|
| keywords | |
| Mechanical properties | |
|---|---|
| Linear shrinkage | < 0.1% |
| processing | |
|---|---|
| Viscosity Comp. A | 40,000 mPa·s |
| Viscosity Comp. B | 40,000 mPa·s |
| Pot life at 23°C | 60.0 min |
| demolding time | 150.0 min |
| Physical & Thermal | |
|---|---|
| Density (23°C) | 1.1 g/cm³ |
| Temperature resistance (duration) | -50 to 200 °C |
| Peak temperature (short-term) | 200 °C |
| storage | |
|---|---|
| Shelf life in original packaging | 12 months |
| Storage temperature | -5 to 30 °C |