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Old 01-06-2017, 12:02 AM   #11
lagfish
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Join Date: Aug 2016
Posts: 45
Re: Travel Float / Bag Stiffener Build

Quote:
Originally Posted by phil herranen View Post
The company's that make surfboards out of xps and xtr use hot needles to poke holes everywhere to control the offgas , don't worry the foam doesn't suck water and the glass doesn't give the foam any more depth rating than just raw foam (unless you make the glass 1/4 thick )

The air in the foam will allways expand in the sun when the board warms up and any water that gets in threw a pinhole or crack will makeep steam and cause delamination ,no amount of sanding will prevent that , but you should still.sand the foam so the glass has a good surface to bond to , and then after its all glassed heat up a needle red hot and poke around 20 holes threw the glass and you should be fine
I've read some successful cases of builders doing XPS boards without pinhole-ing after glassing. It seems like the delamination can be caused by outgassing or shear failure of the interface. The shear failure can be prevented by roughening the surface of the boards as I've done here with a saw:



The outgassing can be prevented or at least reduced by heating up the boards ahead of time and laying up the top and bottom separated by 24 hours. I'm guessing the wait period allows the gas molecules released and excited by the exothermic thermosetting reaction to permeate through the closed cell foam, or maybe just from the surface. I've put the unglassed foam together with a space heater under a blanket and holding it at about 50C for a day to preemptively outgas.



I don't think steam will be an issue because any water that gets in between the epoxy and foam through cracks can leave that way as well as steam.

Anyway, I don't really care all that much if it delaminates. It's just a piece that needs to float and delamination will not compromise that at all.

I really appreciate the feedback though! Keep 'em coming!
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