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 Post subject: Bad surface after vacuum bagging
PostPosted: Thu Oct 16, 2014 8:06 pm 
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I have made kiteboard using vacuum bagging
Stack was as follow:
vac bag
matt which soak resin (I forgot eng name)
perforated film
2 x 200 g/m^2 glass fabric
wood, second side symetrically

As resin I used epoxy (with styrene), room temperature 17 deg, after applying vacuum I started to heat with something like this for about 5 hours (about 40 deg?)

This is how it looked like in bag photo
After opening it loocked like this:
photo
photo

What happened? can I rescue it somehow? Maybe covering with polyurethane varnish will bring it to life?
How should I avoid this next time?

One more thing, I realized, that heater turned off after 1,5 - 2 hours. Mayby that caused that resin shrinked?


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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Thu Oct 16, 2014 9:09 pm 
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Location: The Naki
What are you worried about? the white bits or the rough surface.

If its a rough surface. Don't worry. Thats just a vac bag finish.

The white bits might be a resin depleted zone? i'm cant tell from the picture.


I'd give it a sand and rip another coat of resin on there. See how it looks.


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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Thu Oct 16, 2014 10:37 pm 
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Yes, it is resin depleted zone. resin lacks between fibers of outer layer in some areas.
Somebody from other forum suggested that wood soaks resin. It has sence since there is pattern of areas with air which goes in pair with pattern from wood. You can see that on photo

Next time I will heat wood before laminating to make it soak more resin during laminating.


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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Thu Oct 16, 2014 10:51 pm 
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Yes the wood does soak up resin.

From here you could either peel, sand the layer off and start again or add a layer of resin over the board. They may recover it.

Theres no point trying to soak more resin into the wood. They is just a waste of resin and will make your board heavy.

On a side note. 200gm matt glass is going to provide very little additional stiffness.


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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Fri Oct 17, 2014 2:27 am 
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Location: Perth, Australia
d21d3q wrote:
Yes, it is resin depleted zone. resin lacks between fibers of outer layer in some areas.
Somebody from other forum suggested that wood soaks resin. It has sence since there is pattern of areas with air which goes in pair with pattern from wood. You can see that on photo

Next time I will heat wood before laminating to make it soak more resin during laminating.


^ What you need to do is seal the wood *before*. Epoxy sealer works ok. Perforated film + bleeder + breather.
Good luck.


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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Fri Oct 17, 2014 9:59 am 
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plummet wrote:
Yes the wood does soak up resin.
On a side note. 200gm matt glass is going to provide very little additional stiffness.

I applied two layers of 200 on both sides.
downunder wrote:
What you need to do is seal the wood *before*. Epoxy sealer works ok. Perforated film + bleeder + breather.
Good luck.

So spreading resin, waiting one or two hour till it gel should be enough before continuing with glass?


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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Fri Oct 17, 2014 3:00 pm 
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:)
Close but no. Sealing is not done with normal epoxy. Epoxy sealer is very thin, like water and must be cured. But I think your problem is film + bleeder + breather.

Think about a bleeder as a membrane not to bleed to the death:)

D.


Last edited by downunder on Fri Oct 17, 2014 3:04 pm, edited 1 time in total.

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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Fri Oct 17, 2014 3:00 pm 
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:)
Close but no. Sealing is not done with normal epoxy. Epoxy sealer is very thin, like water and must be cured. But I think your problem is film + bleeder + breather...

D.


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 Post subject: Re: Bad surface after vacuum bagging
PostPosted: Sat Oct 18, 2014 6:48 pm 
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d21d3q wrote:
So spreading resin, waiting one or two hour till it gel should be enough before continuing with glass?

I did like this and that solved the problem. Surface is without air now (only some scratches made by perforated film, but that is different problem.


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