Why Vac Bag?

just trying to increase my knowledge. i’ve seen a lot of posts in my searches about vac bagging.  can somebody explain what it does, how it works, pro’s/con’s etc.? thanks.


It’s a method of clamping the laminate to the core and subjecting it to some compression while the resin sets up.  Using vacuum enables a more even clamping pressure around the whole board and is more useful when working with certain fabrics or wood or other reinforcements that wouldn’t otherwise adhere to the blank via gravity + resin alone.  


Using vacuum to clamp a layer of veneer to the deck of a surfboard is probably the easiest application.  Wet the blank-side of the veneer out with some epoxy, tape it to the deck of the surfboard, stick the whole thing into a vacumm bag (basically a sealable plastic bag that won’t leak after it’s sealed) and then use a vacuum pump to draw out all the air trapped inside until you pull some vacuum.  The vacuum pulls the bagging material tight against the board and clamps the veneer in place around the contours of the deck.  The vacuum remains until the resin sets up.  When you pull the board out of the bag the veneer is glassed onto the deck similar to what you’d get if you hand laminated a piece of fiberglass cloth to it.  


Or, you can bag a wet lamination of cloth to a blank and subject that to the even clamping pressure so the lam cures tight and compressed and with fewer air bubbles trapped in the lam.  There’s obviously a point of diminishing returns and in real life a skilled laminator using the conventional lam technique can do as well or better with surfboard fiberglass cloth than a less-than-perfect vacuum bagged lam technique.  The vacuum process is more expensive, too, because it uses additional equipment (vacuum pumps, hoses, bag-fittings) and consumables (bagging materials and breather layers and release ply layers).  


The conventional wisdom on Sways is that for standard fiberglass layups most people might as well stick with learning the conventional laminating techniques.  But for building boards with wood or high density foam veneers or using certain industrial fabrics that would otherwise tend to “float” off the blank when using hand lam techniques, vacuum bagging has it’s advantages.  


In real life the shape and design of the board still rule, though.  Materials and construction come second.   

oh ok.  thanks for that. great explanation. 

so for the cork and bamboo laminates it works best.

what about cloth inlays like nocean likes to do?

 http://www.swaylocks.com/node/1028002?page=308  (last post at the bottom)



I’ve never done one but I would imagine it would be one way to wring out the excess resin he says those fabrics soak up.  Probably best if the underlying blank is extremely well sealed.

As I understand it you don’t want to use too much vacuum with wet laminations because you can pull too much resin out and create problems with adhesion and dry spots and pinholes in the lam.     I’ve only done a couple of them myself so I’m not real well informed on them.  A cuople years ago someone who was doing them mentioned that he leaves the lamination slightly “wetter” than when he does hand lams and the vacuum bag leaves a clean no-hotcoat finish.  

If you are just starting out, cloth inlays can easily be done by hand.

Vac bagging is best for adding a skin, or certain cloths that either are too stiff, or so light they float on resin.  Or you are trying to control your resin cloth ratios for higher strength to weight.

For regular loose weave fiberglass, more pit-falls than advantages.  For tight weave cloths and veils, almost mandatory.

Why vac bag?

Parts for Spaceships and F-1 cars are vac bagged.........

I vac bag skins like G-Daddy says.........I don't build race cars or spaceships.....

Have fun!

Good on you. I just read your 'Bio-account info.

Vac bagging is fun, but I imagine at your current level of experience ‘hand laminate’ and ‘Sanding’ and ‘shaping’ should provide just as much fun, Its all good though, Rip In!

All The Best…

…Do U plan on using some sweet pre shapes, or the old dusty plainer method :wink: ?