An experiment in vacuum bagging

A common misconception of bagging is that it's for removing ALL the air in a laminate.
For the application were taking about here, which I feel is more about even clamping pressure, using a vacuum will spread out the clamping force and allow an exacting tolerance of the glue sqeeze out.
The vacuum needs only to be great enough to obtain the desired clamping force, not a total extraction of the air in the lam, which for all real intents is zero with clean and uniformly flat pieces of wood. Further pulling of a vacuum to where the cellular structure of the wood is being pulled will lead to the foaming and by that time the adhesive has been squeezed out and/or the laminates are bowed under the strain.
If you intend on bagging a porous material, ie, wood, open cell foam or a multiple laminate of 'glass, it's best to seal the lams first using a thinned amount of the adhesive, epoxy in this example. Flood on a batch of catalyzed epoxy thinned 50% with MEK and let it start to kick or let it kick fully in the case of a foam like Klegecell, Airex or the like. Then apply a full coat of catalyzed epoxy and apply enough vacuum to get your intended result. Pulling a vacuum with the sealed lams will keep the porous materials from bleeding and thus reduce the foaming and yielsd the correct properties of the materials and the epoxy.
Hope this helps.

very good info right there....would a similar approach work if you were working with a resin soaked material like sheets of FG or CF...i am specifically thinking about making a pole or like the tube portion of a hybrid?
thanks

Yes. If you're working with wet laminates, the vacuum can then be used to assist extracting the air while forming the material around the mandrel. Be careful though to put a wad of absorbant waste material at the vacuum port or the excess resin will back up into the line and then you got troubles.

One other thing that I didn't get into because it'd take a book to go over is the use of bleeder material to evenly apply the pressure to a wet laminate and the absorbant material to soak up th eexcess resin prior to applying the heat for a full cure. Think of the bleeder as a sheet of plastic punched full of pin holes that let the resin squeeze out and get absobed by a diaper and that'd be close enough.

Cool got it. Sort of a double bag where one acts as a semi permeable membrane. Any tips on the mist effective absorbers? I would think fleece right?

Yes. If you're in SoCal and they're still in business, RAM chemicals in Pacoima sells bleeder and also the needle roler to make your own out of 2.5-4 mil plastic sheet. As far as cheap absorbant you can split up some disposable diapers or go to a fabric place and buy a few yards of the dead-cheapest felt they have. Fleece is way too spendy for this application.