closed cell foam

[Boludo]

So I was doing some research on this closed cell foam, actually looking at the XTR foam. 

"The main advantages are strength and imperviousness to water absorbtion. It is very resistant to impact and compression."

Am I missing something or is there much more to this?  It seems to me that shapers should be using this type of foam.  They claim it to be 40-50% stronger.

[Celeste]

Density? availability? cost?  does it react with resin?  how easy is it to shape?

[getsupngo]

Extruded polystyrene also adds a really nice feel to the ride.  Be extra careful with it in the heat.
Epoxy is fine but make sure its left rough sanded for a good mechanical bond.

Things like a lighter board and even the types of foam used in it can open up perceptions to some of the other dimensions a board can have.       

[supuk]

i found this the other day and it looked quite interesting for a deck sheet

http://www.3d-core.com/en/products.html

some closed cell foam are very ridged and hard to work. i used corecell on a hollow moulded board i did, the only way to get that to bend to a rail curve was to heat it and there is no way you would be able to do that with a foam core underneath but it has supper good impact resistance while other foam are easier to form but lack in the other areas.

[Boludo]

So I've been intrigued just from reading about these XTR boards/blanks. 
A few things that I've captured that I like so far:
1.  Doesn't hold water
2.  Stronger
3.  Light weight (still unsure if it's lighter than most blanks)
4.  More buoyant, according to Bethany Hamilton.  http://bethanyhamilton.com/partners-sponsors/xtr-epoxy-pro/.  This could be an advantage if you could thin out a SUP a tad more than usual.

Anyways, I just do this research out because I enjoy learning about different technologies and possible ways to improve a board and appreciate the knowledge and feedback of my fellow zoners.
I'm just thinking out loud.

[peterp]

XTR has been around for a while and is great until it delams.....every shaper will tell you he has cracked it.....but they all do it eventually. It's a shame because you can make really light strong boards with good flex characteristics....

[Boludo]

peterp,

That's exactly what I was reading however I was thinking with more time that has now passed, more development has been done to let gasses escape.
I just read this:
"However, some companies (such as Channel Islands) have made huge developments in XTR-constructed boards, finding ways to allow the gases to escape without compromising the integrity of the surfboard."

So question for you:  What happens when a board delams?  Can it be fixed at a reasonable cost?

[PonoBill]

Define "fixed". Does that mean as good as it ever was, or useable. You can make a delammed board usable.

[Boludo]

good as new excluding cosmetically

[peterp]

I just read this:
"However, some companies (such as Channel Islands) have made huge developments in XTR-constructed boards, finding ways to allow the gases to escape without compromising the integrity of the surfboard."

There's that claim again....

[Boludo]

More info on their way of venting it.  As far as surfboards go, it seems at least 9/10 love the feel and durability of XTR.  Not bad considering you can't please everyone.


quote from their website:
Quote

"THERMOVENTS"
WHAT IS "THERMOVENT" TECHNOLOGY?
All Surfboards glassed at Epoxy Pro after June 2002 come with "Thermovents", a patented solution that eliminates the bubbles due to heat or use on the deck and rails of your XTR surfboard. "Thermovents" are small vents that penetrate the fiberglass to the surface of the foam allowing gas to escape when hot (all XTR blanks have gas inside each small cell, it makes the surfboard more responsive and resistant to aging).
Water cannot penetrate the foam because XTR is closed cell foam, only a small amount of moisture will get inside the vents, nothing that will alter the weight or strength of your surfboard.

WHY DO SURFBOARDS NEED "THERMOVENTS" ?
Epoxy Pro has been making surfboards with Extruded Polystyrene Foam since 1991. All the surfboards made with these materials by Epoxy Pro or any company will in the long run bubble or blister under your front feet or rail due to the gas inside the foam.
Hundreds if not thousands of stoked customers were eventually calling with a complaint about a bubble or a delamination on their surfboards.
Many sleepless nights and countless ideas were spent trying to solve the bubbling or delamination problem, until one day, in June 2002, Javier and his son Diego started to vent a surfboard that was a year old and start a set of temperature tests until they discovered that the surfboard did not bubble!! Even at 140'F.
Since then the vents have been perfected and also added to the rails of all short boards in 2004.

HOW THERMOVENTS ARE APPLIED TO THE SURFBOARD?
Javier has designed and also patented a special tool that reaches 200'F and penetrates the glass all the way to the foam. This tool is applied after the surfboard has been finished.
This tool is made with special needles that conduct heat to melt the outer layers of the fiberglass and resin without debilitating the surfboard. It takes less than 1 minute to apply the vents and they are almost invisible.  end of cuote.

[SUPflorida]

I keep hearing that...but I have two windsurf wave boards (1993 & 1994), a surfboard (1996), live in florida...all three have baked on numerous occasions in the camper shell of my Dark green Dodge 4X4... and these three, as well as many others were made with the closed cell foam purchased from Doug Wright years ago and have never delaminated from the south florida heat to this very day...all done with RR epoxy.

[finsider]

Closed cell extruded foam is great for the fact that it does not absorb water, but it also does not absorb resin like an EPS foam will.  The XPS also has a "finer" surface so getting proper adhesion to the resin and fiberglass is the key to making a board this way.  I have heard of people scuffing the foam to promote resin adhesion. It can and has been done, and works beautifully. It is however more tedious of a job which is why some shapers stick to EPS.

From a shaping standpoint it is a tougher cut, but extruded foam will not come off in chunks like some lightweight EPS will.

[SUPflorida]

I didn't rough up the foam or do any special treatment...at least sanded down to 120 probably 220. To me it was a heavier alternative to vacuum bagging Divinycell on 1 lb EPS ...more weight but faster build and no water absorption issues.

[getsupngo]

The trick is to keep the lighter stuff protected from too much shear, cell crushing, and heat.
 
The heat is not much of a problem if the cells dont ever get crushed. Too many crushed cells equals a pocket of gas that expands readily with heat.  Protect the cells from being crushed with a thick strong sandwich over it or just dont use xps wherever its cells will eventually get crushed.

The sandwich can also help with shear by keeping the board from overflexing.  A rough texture before glassing and plenty of epoxy saturation into it also helps shear.