Vacuum bagging ???

[Bluebat]

I’ve build my first kiteboard with the vacuum bagging principle. The board came out very nice, except for a few air bubbles on the bottom of the board.

I must have done something wrong, because I made sure that all the air was out before I VB it.

I’ve put the epoxy and glass on the corecell and made sure all the air was out. Then I put I Layer of peel ply on both sides, put the board on the rocker table and then put everything in the vacuum bag.

Should I have put the board in the bag and then put it on the rocker table?

My rocker table have a concave, how would I get this on the board then? 2 Bags?

[4T]

hi bluebat,

did you use any perforated release film and breather cloth on at least one side of your lay-up?

you need to help the vacuum migrate evenly throughout the bag.

i use a perforated release film on the top to let any trapped air through but it stops resin bleeding into the breather cloth. you can either buy proper breather cloth [polyester vlies] or use a couple of layers of paper towels.
if you only use the breather on the top you might want to punsh a few holes through the foam with a thick needle to release any trapped air from the bottom.

hope this helps

[crabman]

Bluebat the pin holes are caused by the release . You should be able to vacuum in one hit onto the concave without any problems . No pin holes= no release ,just use peel ply and breather.Honest it works.

[Bluebat]

Thanks for the advice.
I’ve used peelply on both sides and I’ve use normal nylon cloth on the top for a breather cloth, but not on the bottom

So if I put a breather cloth between the board and the table it would work?

[crabman]

For a breather use the correct stuff its worth it. You dont need a breather on the base .You need to vacuum the board to your rocker table as hard as you can . Use peel ply top and bottom and breather only on the top . For the base of the board you need to use a clear film which will come away with the board when done so it doesnt stick the board to the rocker table .

[4T]

i would certainly recommend using a perforated release film between the laminate [inclusive peelply] and the breather.

if you place the breather directly onto the peelply and pull a hard vacuum you will have uncontrollable resin bleed from the laminate into the breather and could end up with a dry laminate.

the perforated release film is just very thin plain plastic film with tiny pin holes about 2cm apart in it.
it lets air through, but keeps the resin in the laminate.
the roll i bought cost about 50cents a metre.
well worth it.

[crabman]

4T have you tried it without.I bet you get pin holes using it .In 25 years we have never used perforated release. Still everyone has there own ways

[Bluebat]

Thanks guys

The nylon material that I used was very wet from the Epoxy, so that must have been the problem.
If got the breather cloth and will try it on my next attempt. It just looks a little thick. Will let you know how it goes.
Thanks again

[4T]

4T have you tried it without.I bet you get pin holes using it .In 25 years we have never used perforated release. Still everyone has there own ways

hey crabman,

there sure are different ways to cook the goose.
i don't doubt that you have worked out a technique that suits your product.

but to understand a bit better how you are doing it, you might be so kind to answer a few questions. i'm always keen to learn.

when and how do you wet out your cloth?


how much resin does get transfered into your breather cloth? is it saturated when the resin has set? do you anticipate the amount of resin that transfers into the breather and add it to the laminate?

and yes, i have tried without the perforated release film and it kinda works, but i find it hard to control the amount of resin which stays in the laminate and no i don't get pin holes from the release film because it's perforated and lets the air out into the breather cloth.

cheers
boogie

[crabman]

4T if we use wet lay up ,we wet out on the product .Resin amount transfered onto breather depends on the choice of peel ply and thickness .
This governs the resin .Weigh breather before and after to find resin ratio wastage. No its not saturated. Yes we do anticipate resin amount .Use to use pre preg .
We also use resin infusion. And no we dont sand our products to get a finish Once resined ,thats it finished .Our boards are made in one hit