benefits of vac bag'n the lam layer

can anyone justify baggin the final lam layers?

what are the pros and cons?

totally depends on the board you are building.

Straight up foam the benefit would be optimal strength to weight characteristics, consistant quality for the specific size board.

Composites are as above but it also would depend on if there was a need to trim and reshape whatever you are putting on the board. Example: foam,fiberglass, wood composite surftechs have no fiberglass on the outside of the shell, just a polyester finish.

another instance is when using carbon fiber, kevlar weaves the vacuum will allow less resin to be used and better conformity to the board versus trying to lam by hand.

so in some cases it would be essential to the manufacturing process and other times not necessary. do you have a specific scenario in mind?

can anyone justify baggin the final lam layers?

what are the pros and cons?

The pros are:

  • a lighter board with the same strength and less cracking

  • a final finish that doesn’t need a hot coat

  • it can ultimately be faster

The cons are:

  • you need the vacuum equipment and supplies

  • it may take longer to glass this way until you have a few under your belt

In the end, I don’t think there are any huge advantages unless you are looking to automate the glass process for production. Personally, my glass jobs just come out better with very little effort. If you have the equipment, I think it’s worth trying, at least on a test panel. You never know, you might like it better.

Options…it’s good to have options.

“- a final finish that doesn’t need a hot coat

well thats interesting cuz it seems that most of the info you read about vac’n suggests optimal fiber/resin ratios…trouble is, in surfboards the outer lam has multiple functions:

  1. adds strength and stiffness

  2. waterproof seals the core

  3. surface finish, both performance and cosmetics

so the whole fiber/resin ratio argument didnt hold water in my head…an optimal fiber/resin ratio for strength/weight may not be optimal for sealing and surface finish…so why bother baggin to maximize fiber/resin ratio when you then gotta lather the lam with a hotcoat to seal and sand smooth…???

well thanks Kenz, I’ll have to do a test panel (someday not soon) to determine whether a hotcoat can be minimized or even avoided…I’ll admit though, my hand layups are pretty darn good…vac’ns gotta be substantially better for me to be interested…perhaps it is…to be continued

If you vac the lam, you shouldn’t need to hotcoat to fill the weave of the cloth, only pinholes. It does seem a shame sometimes to do a really neat lam by hand, then throw it in a bag for it to come out not looking as nice as it went in!!! When using wood skins and some foams, the fact that it is in a bag does stop any gassing/airbubbles that may occur in a hand epoxy lam