Author Topic: Just thinking out loud...  (Read 3478 times)

sharksupper

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Just thinking out loud...
« on: April 22, 2018, 05:32:28 PM »
I spotted all these materials around my shop.  Dow high density blue foam(loads of it), honeycomb core material, and plenty of carbon.  Hmmm  what could I do with all this...

With how some foil board shapes look these days, a few cuts with my hotwire and I bet I could have something maybe ridable.  What do you think?  Should I give it a shot?

jrandy

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Re: Just thinking out loud...
« Reply #1 on: April 22, 2018, 06:39:40 PM »
It looks like you are set. I was thinking of something from the EPS offcuts I seem to collect.
http://pushheretosavealife.com/
Be safe, have fun. -J

sharksupper

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Re: Just thinking out loud...
« Reply #2 on: April 22, 2018, 07:31:50 PM »
I'm wondering if this foam I have is the right choice.  It's about 6 to 6-1/2 lbs for 100 Liters of it.  Then again, I wouldn't need a strong of an outside layer.  I guess I could just cut holes in the core to lighten it.  It does look nice to carve though, probably doesn't tear as bad as lightweight EPS.

jrandy

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Re: Just thinking out loud...
« Reply #3 on: April 22, 2018, 08:04:24 PM »
I have never shaped a board from XPS.
What I remember is people try to leave the surface rougher than normal to give tooth to the resin.
http://pushheretosavealife.com/
Be safe, have fun. -J

surfcowboy

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Re: Just thinking out loud...
« Reply #4 on: April 22, 2018, 10:08:25 PM »
XPS = delams, if I'm not mistaken.

I made a handplane out of that a few years ago. It blew up like a balloon. I'd out in a vent at least. Or just get some EPS. It's pretty cheap.

sharksupper

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Re: Just thinking out loud...
« Reply #5 on: April 22, 2018, 11:17:03 PM »
XPS = delams, if I'm not mistaken.

I made a handplane out of that a few years ago. It blew up like a balloon. I'd out in a vent at least. Or just get some EPS. It's pretty cheap.

Yes, I've read about the woes too, were you vacuum bagging it?

jrandy

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Re: Just thinking out loud...
« Reply #6 on: April 23, 2018, 05:17:52 AM »
BJ, I am not sure EPS (smashed together beads) and XPS (solid extruded) react the same way in regards to venting. 
http://pushheretosavealife.com/
Be safe, have fun. -J

Biggreen

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Re: Just thinking out loud...
« Reply #7 on: April 23, 2018, 10:18:09 AM »
We have a buddy that's ridden his home built XPS boards for years without issue. You don't want to take sanding of your foam smoother than 60 grit, rougher even better. 20 grit is ok. He hand layed up all his boards without problems. Hell, he even went so far as to contact Dow Chemical and talked to a chemist who said the out gassing thing is BS. He has taken these boards to Mexico for years, that way there's no repair issue if you punch a hole in one. AND he's the guy that doesn't use surfboard resin. Never had any problems there either. I've seen many of his boards that are YEARS old and doing fine.

Keep your blank rough. That's the key to good adhesion.

PonoBill

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Re: Just thinking out loud...
« Reply #8 on: April 23, 2018, 11:12:01 AM »
I use a lot of XPS for patches and cassettes. I've never shaped a board with it, for the simple reason that I've never shaped a board, but I like it a lot. The weakest XPS is two times stronger than the strongest EPS, and you could use it bare without taking up water. If there's a delam problem I've never experienced it. I also haven't coarsened up the surface. The finished surfaces of XPS are very smooth. I didn't know there's supposed to be a problem, so I've never done anything to that surface. Never had a problem though the areas of XPS I've used aren't huge. Probably the biggest is the mast track cassette in my L41. I vacuum bagged that with a nearly rail to rail patch of carbon. If it delams we'll never know. The carbon is probably the stiffest and strongest part of the board. Two layers of 6oz 3K.

When I get back to HR I think I'll shape a foil board with it.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

sharksupper

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Re: Just thinking out loud...
« Reply #9 on: April 23, 2018, 01:50:53 PM »
If I understand XPS vs EPS correctly one big difference is that EPS can "breath" throughout it's whole structure, ie air can get from one end of the board to the other with no hindrance.  Whereas XPS is sealed off, air cannot move around the core.  Seems like the XPS would be great for staying waterproof!  But if something gasses out (creates some kind of air pressure) within the structure of a sealed up XPS core, where is it going to go?  Even if you have a vent plug how would the pressurized air get to it?  Perhaps that's the reason for delam issues people speak about?  I'm really not sure what would even cause a formation/rise in air/pressure within if properly vacuum bagged, is that possible?

Bean

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Re: Just thinking out loud...
« Reply #10 on: April 23, 2018, 06:13:56 PM »
It's really the internal and external, temperature and pressure, differential.

surfcowboy

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Re: Just thinking out loud...
« Reply #11 on: April 23, 2018, 07:43:45 PM »
I'd love it if this is all true. I like xps a lot. Just sharing my experience and there's a ton of talk on Sway's.

I can see that leaving it rough would get you there. Or venting even. Point well taken on the EPS openness vs XPS being solid and closed cell. However there's still got to be room for air between the blank and glass and maybe that's what blew this thing up like that?

Bagging is always better imho for sure. Maybe that's get it? I say go for it based on BigGreen's experience and that's not me being sarcastic, I trust it. Worst case you can still ride an epoxy board with delays for a long ass time til you have issues. Hell im like 5 years in on a poly longboard that's got a giant delam and I have no plan to turn it into a wall hanger til it opens up.

PonoBill

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Re: Just thinking out loud...
« Reply #12 on: April 23, 2018, 11:58:18 PM »
If I understand XPS vs EPS correctly one big difference is that EPS can "breath" throughout it's whole structure, ie air can get from one end of the board to the other with no hindrance.  Whereas XPS is sealed off, air cannot move around the core.  Seems like the XPS would be great for staying waterproof!  But if something gasses out (creates some kind of air pressure) within the structure of a sealed up XPS core, where is it going to go?  Even if you have a vent plug how would the pressurized air get to it?  Perhaps that's the reason for delam issues people speak about?  I'm really not sure what would even cause a formation/rise in air/pressure within if properly vacuum bagged, is that possible?

The breathing aspect is not a plus. A lot of the bubbles that make EPS pop in the process of making it, so the interstitial area is connected, which means gasses can diffuse through the structure and water can soak in. Once water enters its hell to get out since surface tension holds it in place. XPS expansion is tightly controlled in the extrusion process, so very few bubbles pop. The structure is more uniform and the polystyrene matrix is more connected and consistent, so it's stronger. The offgas "issue" is debatable. Not that it doesn't happen, it does, but rather what effect it has. The blowing medium for XPS used to be CFC, but after the ban that was switched to HCFC, which has many less desirable properties but for our use, it's kind of cool since it mostly stays put. Other alternatives are Pentane, other HCFCs, and water. I think the CFC XPS is likely the culprit for prior problems since it slowly offgasses and was replaced with air. If it just made its way out of the rigid bubbles it would cause issues since the thermal expansion of CFC is large. Both pentane and HCFC have lower expansion coefficients.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

 


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