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Wrinkles, WTF

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downunder
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Re: Wrinkles, WTF

Postby downunder » Sun Sep 06, 2020 5:06 am

Others might disagree, but,

The vac bag should have quite big "foldings" to compensate for bridging etc. I know. Im not using this enough myself. And just yesterday pulled a new board from a bag ;) Not happy, its a bit dry, on only 20hg.

If there was a mid layer peel ply between this might not happen, I think. Plus, if the bag was folded in a few places, any wrinkles would happen there only. That is only if it happens. This is coz a folded bag would create a "highway" for air to suck epoxy in there. Not everywhere else, but there. With no highway, epoxy just stays trapped.

D.

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Re: Wrinkles, WTF

Postby TomW » Sun Sep 06, 2020 9:10 pm

This is what your bag should look like on the lam side. It's all bunched up on the other side.
PhotoGrid_1599422954497.jpg

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Re: Wrinkles, WTF

Postby Erinhdisc » Sun Sep 06, 2020 10:44 pm

Can I leave off the release film and just go laminates, nylon peel ply, breather, bag? Thank for all other suggestions. Strangely enough, the bag looked just like your photo with all the bag wrinkles on opposite side of layup. My wrinkles came from perforated film directly on layup, and not from my bag.

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Re: Wrinkles, WTF

Postby dirk8037 » Sun Sep 06, 2020 11:47 pm

>>>The vac bag should have quite big "foldings" to compensate for bridging etc.<<<
I agree with that.
The evenly streched bag caused for me in the past quite a lot of bubbles of trapped air because the surface had slight dents.
I also agree that its excess resin.
Peelply helps to a certain part but it does not prvent that phenomenon.
I wonder if your plastic layer had enough wholes in and if on the other side was enough capacity to absorb the resin.
Also too low pot time might enforce that.

If you look the pic of tom. It displays quite perfect amount of resin used for the laminat. In the vacuum little gets sucked through the perforated barrier and is absorbed by the fleece or what ever he is yousing (I do it with 2-3 layers ofkitchen paper).
If the dots start to connect the fleece is getting saturated and the resin stays wher it is.

The real Peelply also takes a bit of resin if you put it dry on the laminat.
But i once did it without, resulting in a slick surface with little dots. The sanding then would harm the glass ...

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Re: Wrinkles, WTF

Postby downunder » Mon Sep 07, 2020 2:40 am

TomW wrote:
Sun Sep 06, 2020 9:10 pm
This is what your bag should look like on the lam side. It's all bunched up on the other side.
PhotoGrid_1599422954497.jpg
As mentioned, two schools of thought!
IMG_20200906_223324.jpg
I can also say that this is how bag should look like ;)

Will open it in 8 hrs and let you know the result.

Here is a question: did you try to tension the bag to get the bag as on Tom's pic?

Because if you did, I think that created wrinkles.

Erinhdisc wrote:
Sun Sep 06, 2020 10:44 pm
Can I leave off the release film and just go laminates, nylon peel ply, breather, bag?
no. It is not worth experimenting with this I'm afraid. Only if you have huge amount of time and resources.

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Re: Wrinkles, WTF

Postby Jyoder » Mon Sep 07, 2020 3:16 am

The original poster didn’t use peelply right? Just perforated film? No wonder it wrinkled.

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Re: Wrinkles, WTF

Postby Jyoder » Mon Sep 07, 2020 3:20 am

Erinhdisc wrote: ↑
Can I leave off the release film and just go laminates, nylon peel ply, breather, bag?
no. It is not worth experimenting with this I'm afraid. Only if you have huge amount of time and resources.
In my very limited experience, release film or perforated film over the peelply is not needed if you wet out the laminate cloth correctly and you use quality peelply.

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Re: Wrinkles, WTF

Postby merl » Mon Sep 07, 2020 7:54 am

downunder wrote:
Mon Sep 07, 2020 2:40 am


As mentioned, two schools of thought!

I've seen awesome pics of both yours and tom's builds so clearly they both work, but putting creases on the deck seems to add a risk to me.
Can you explain your school of thought again? It seems in both cases (in the pictures) there is pretty much the same even flow of excess epoxy from the laminate to the breather, but one has creases in the film and one doesn't. What do the creases bring to the game?

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Re: Wrinkles, WTF

Postby downunder » Mon Sep 07, 2020 9:14 am

It is simple, really.

https://d2n4wb9orp1vta.cloudfront.net/c ... ;width=560

https://commercecontent.azureedge.net/0 ... leat-G.jpg


https://precat.nl/en/2013/09/

"Every 34-45 centimeters we create creases to ensure sufficient space for the bag to shape itself once the vacuum pumps are running."

https://precat.nl/en/foam/vacuum-infusion-hull-side/


I can get away with no creases b/c the surface is small. However, any bridging and CF will not bridge. I see this on some spots on Tom's pic. I also see uneven pressure, but maybe that was fixed after. The breather must overlap complete surface, and where the tape was will be clearly visible, needing some TLC.

Now I'm gonna open the 'magic' bag...:) Oh, and I've moved the board in the bag, so the creases were not positioned right, but hey, was 10.30pm yesterday...

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Re: Wrinkles, WTF

Postby TomW » Mon Sep 07, 2020 9:58 am

this is a really good topic, and i appreciate everyones experiences. I definately have not stopped learning. Vbagging is fairly complex and requires experimentation and that can get expensive if you mess it up.

If you are new to this, you should stick to the recommened method of peelply-perf film- absorber methond to start.
Ive found the peelply keeps the weave in place and resists any deformation of weave when manipulating the bag, and it absorbes any excess resin avoiding resin " ridges".
The perf film controls the outflow of resin to the absorber- my pic shows that there are areas with more resin due to multiple layer and/or not a raw blank under it. So the perf film is regulating flow, allowing absorbtion where needed and not where it needs to stay in the laminate.
The absorber can and should go all the way around the rails, but I´ve found there is risk the absorber causes wrinkles on the rails, especially when they are so tight like on these boards. So i dont do that and let the peelply do the absorbtion on the rails. Theres a bit more clean up, but i find its safer this way.

Not using perf film is done by some, and use only peel ply and absorber, but you have to be careful to not overdo the pressure in the bag becuase the absorber can suck up too much epoxy leaving the laminate dry.
Perf film is so cheap, i dont see the reason to not use it as it is " regulator" of uneven resin wetout and layers.
please note that even overdoing pressure WITH perf film can suck out too much resin. This is particular to each situation of how much resin is in the laminate and how much is getting absorbed into any pourous underlying core.
A variable here is that all perf films are not alike- some haver more holes than others. So that effects the perf films regulation level.

when it comes to bunching the bag up, based the reading and video watching i´ve done, is that bunching up is needed with complex shapes that may result in bag " bridging". generally a kiteboard doesnt have this complex and radical complex/concave shapes like say a rearview mirror housing for a car. What ive seen, the bunching is done in negative forms when laminating into a mold.
What kind of bag material you are using is important too. Some bag materials are not stretchy at all, some are very stretchy and bridging is less of a problem.
I also did some bunching of the bag on the laminate at first, but found the bag wrinkle can " pinch" the laminate or consumable layers and cause a wrinkle. Had some messes then..
Just my experience- totally respect if someone figures it out- because bridging can be a problem.

I´ll debag tonight and post some pics. Good luck!
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