Connecting you to the composites industry


Vacuum Bagging

  • Friday, 25th January 2019
  • Reading time: about 2 minutes


This is basically an extension of the wet lay-up process described above where pressure is applied to the laminate once laid-up in order to improve its consolidation. This is achieved by sealing a plastic film over the wet laid-up laminate and onto the tool. The air under the bag is extracted by a vacuum pump and thus up to one atmosphere of pressure can be applied to the laminate to consolidate it.

Materials Options

Resins: Primarily epoxy and phenolic. Polyesters and vinylesters may have problems due to excessive extraction of styrene from the resin by the vacuum pump. 
Fibres: The consolidation pressures mean that a variety of heavy fabrics can be wet-out. 
Cores: Any.

Main Advantages

  1. Higher fibre content laminates can usually be achieved than with standard wet lay-up techniques. 
  2. Lower void contents are achieved than with wet lay-up. 
  3. Better fibre wet-out due to pressure and resin flow throughout structural fibres, with excess into bagging materials. 
  4. Health and safety: The vacuum bag reduces the amount of volatiles emitted during cure.

Main Disadvantages

  1. The extra process adds cost both in labour and in disposable bagging materials 
  2. A higher level of skill is required by the operators 
  3. Mixing and control of resin content still largely determined by operator skill

Typical Applications

Large, one-off cruising boats, racecar components, core-bonding in production boats.

Published courtesy of David Cripps, Gurit

Share this article

Continue to Filament Winding Back to Wet/Hand Lay-up

Comments (0)

Sign in or create an account to join in the discussion.

Leave your comment


Upcoming Events




Follow us
Subscribe to our email newsletter

Subscribe to receive our weekly round-up of all the industry's latest news, jobs, events and more!

We'll always keep your personal details secure and will never share them with third parties for marketing purposes. You can unsubscribe at any time. For further details on how we may use your data, please visit our Privacy Policy.