Vacuum question

I'm about to build a board and have questions about vacuum setup (which I so far have only used for small repairs). The board will be a long (DW) EPS wing board with a d-cell layer only on top.

1. Which layers are really needed? The place where I usually buy supplies has peel ply, breather, perforated release film, and vaccum bagging film. Do I need them all? Can some be left out, replaced with cheaper sources, or re-used? In particular, do I need all that for the first step of putting the d-cell on the EPS?

2. Should I use vacuum for both bottom (no d-cell) and top?

3. Does it make sense to use vacuum for the "hot coat" layer? I have built a couple of wing boards following standard surfboard steps without vacuum, but I have had quite a bit of problems with pinholes and bubbles. Part of the issue is that temperatures vary a lot over the course of the day. I'm thinking that using a light vaccum (and a slower epoxy to have time to bag) may help that.

Thanks for any experienced-based suggestions.

I don't use perforated film at all any where. It only works on flat surfaces.
The only problem with the first d-cell layer, is resin that squeezes out into the bag, this can puncture the bag if you reuse it.

I vacuum the final glass layers, but this removes resin, and can create more pin holes, not less. But will increase the fibre to resin content and reduce the weight significantly. I then use a very thin slurry of q-cell as a filler on the deck, and a thicker layer on the bottom so I can sand it smooth. The deck stays virtually straight out of the bag

Thanks guys. Sealing the EPS core before laminating is new to me, but I've found some references now. My first 2 boards were PU (long time ago) and XPS, so that was not an issue. With the last board in EPS, that certainly would have been a good idea. I saw suggestion to use Polyfilla Big Holes patch, but I'm worried about that reducing strength, relative to using epoxy with q-cells and fumed silica.

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decrepit said..
The only problem with the first d-cell layer, is resin that squeezes out into the bag, this can puncture the bag if you reuse it.

I'm reconsidering using weights instead of vacuum. The XPS board eventually delaminated between the core and the d-cell layer, developing a big bubble. But I did not prep the XPS much, and may have used too little epoxy. That definitely happened with the EPS board, where I had to glue the sides down with Gorilla glue. But that board held up well.

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lemat said..
Yes vacuum bag lam allow an high fiber/resin ratio wich give best strengh/weight ratio, for tensil in fiber direction stress. Board skin mostly don't break because of tensil stress but because of buckling (flexural instability under compression) or shear impact. For those mechanical constraints ideal fiber/ratio is not the same.

The most common problem I've had with various purchased boards is punctures and dings from shells, small stones, etc. Are you saying that a bit more epoxy would be better to avoid this kind of damage? I don't care if the board ends up heavier if it ends up more ding resistant. My primary motivation to consider vacuum was to reduce bubbles (where it would work) and pin holes (where it may actually make things worse, according to decrepit).

Light weight spackle work but i like more epoxy micro slurry that give a stronger surface so you can squegge better lam over. If you don't care with weight hand lam couple layer of sglass with good epoxy, well squegged not too dry but not with resin pool. Let dry, when tacky hot coat. I use mid viscosity fast setting epoxy designed for hand lam.

Have a look at Mat G videos how he does it.

?si=2abD45geatPDmxYj

Love the hot wire tape trick

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catchmeifucan said..
Have a look at Mat G videos how he does it.

?si=2abD45geatPDmxYj

Thanks so much for posting this video! Just watched the first few minutes so far, but already saw many neat tricks that will be really helpful. I'm also starting with 4 ft long foam blocks, and ran into the first problem trying to put them together with spray glue. That failed for multiple reasons, so PU glue it is. Just watching how he does that part already solves a bunch of questions I had. The way he cuts the outline in 2 steps is just genius. I'm sure there'll be plenty of more gems later, too. Thanks again!

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Mark _australia said..
Few tricks in there that I am p!ssed off about

sorry, did i re-invent some industry secrets ?

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lemat said..
This is one way to do it but never like lam on table. I like to spread a thin layer of resin+silica gel texture on sealed eps, then lay flat fiber on it then laminate over with squegge and roller. Mastic before fully cure, no sand lam. For me it's better to set rail plate with fiber and epoxy than pu glue then need less fiber over. I like to connected us rails more seriously to deck and do deck under feet stronger but may be overbuid.

Agree.