Adventures in vacuum bagging

I just finished the external lamination of a board using Zylon and wound up with a small wrinkle on the rail. Gripes me no end! The compound curves make vacuuming the external lamination a challenge.

One of the issues with lapping the rails using the bag is getting the material to cover a tucked rail on the bottom. The Zylon is so stiff that it can't be hand laminated, it pulls away from the board. To avoid a seam on the rails, I want the lap to extend to the deck and bottom.

One trick that seems to have merit involves a pedastal and backer.

The backer extends the film out past the rails and pedastal gives the film a place to get pulled into.

That process was the best for getting the fabric under the tucked rail, but still left wrinkles on the surface. Not in the fabric, but it would leave resin veins on surface.

The next thing I tried was a bag-in-a-bag. I took a small sandwich bag and sealed some air in it, then placed that on the surface of the fabric. The concept being that the external bag would put pressure on the inflated bag and smooth out the surface of the laminate.

The theory is cool, but in practice, the vacuum burst the seal on the sandwich bag and let the air out, where it was promptly evacuated by the pump.

Lastly I tried doubling the height of the pedestal and that shows some promise. The dimensions of the backer and the pedestal will impact the amount of wrinkle left on the compound curves. I think lastly, the bag material needs to have considerable stretch. The consolidation of the fabric is pretty easy, more stretch before failure in the bagging film, I believe, will allow it to conform to the compound curves and move the pleats to below the board and inward toward the pedestal past the rail laps.