Silicones for Vacuum Bagging & Composite Production

See how silicone vacuum bags are made and applied in composite production:

• Reusable – silicone vacuum bags last for tens to hundreds of cycles, unlike disposable nylon film
• Temperature resistant – suitable for autoclave processes up to 200°C+
• Chemically resistant – resistant to epoxy, polyester, and vinylester resins
• Excellent elongation – adapts to complex geometries without tearing
• Vacuum tight – no leakage, consistent pressure build-up across the entire laminate
• Cost-effective – lower material costs per cycle with repeated use

Wacker ELASTOSIL® C 1200 A/B is the reference product for casting reusable silicone vacuum bags. This 2-component platinum-cure system is specially developed for composite production and offers:

• Excellent temperature resistance – stable up to 200°C, suitable for autoclave curing
• High elongation and resilience – adapts to complex shapes and returns to its original form
• Long lifespan – resistant to repeated thermal cycles without degradation
• Low viscosity – easy to pour over molds for uniform bag thickness
• No shrinkage – platinum-cure system for dimensionally accurate bags
• Resistant to resins – no inhibition by epoxy, polyester, or vinylester

Applications: Reusable vacuum bags for autoclave, out-of-autoclave (OOA) processes, RTM (Resin Transfer Moulding) membranes, and press bags for composite presses.

▶ View Elastosil C 1200 A/B

• QVB 701 – 2-component platinum-cure molding silicone especially for vacuum bags and composite production. High temperature resistance, excellent elongation, and long lifespan during repeated autoclave cycles. Reusable for tens to hundreds of cycles.
• SilSo Lite 21025 / 21030 – lightweight silicone foams for gap-filling, thermal management, and sealing in composite structures. UL94-V0 flame retardant (21030), ideal for aerospace and EV applications.
• ALPA-SIL 97116 – fast-reacting platinum-cure system (pot-life 2 min) for rapid prototyping of vacuum bags and composite molds. Demolds in 2–3 hours for high productivity.
• CHT Release Coatings – silicone release agents and release coatings for molds and tools in composite production. Ensure problem-free demolding of epoxy and polyester parts.
• Silicone sealants (AS-series) – for sealing vacuum lines, connections, and edges in vacuum bagging setups. Resistant to high temperatures and chemicals.

• Prepare mold: use a suitable release coating on the mold for easy demolding of the silicone bag
• Pouring: pour the silicone calmly and in thin layers to minimize air entrapment; vacuum degassing recommended
• Thickness: a bag thickness of 3–6 mm offers the best balance between flexibility and durability
• Curing: allow to cure fully at room temperature or accelerate at elevated temperature (post-cure)
• Maintenance: clean with isopropanol after use; check for tears or damage before reuse