Author Topic: XPS Board Building Advantages vs EPS Foam  (Read 2353 times)

Beasho

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XPS Board Building Advantages vs EPS Foam
« on: February 05, 2023, 06:00:12 AM »
The following are observations from building a board with XPS foam. These are the benefits:

   The foam has a compressive strength of 20+ psi (pounds per square inch).  This means that the foam can handle a full 100% vacuum.  This is significant because it allows for full vacuum pressure (always slightly less than 15 psi). 

   The foam is structural in nature, much more than EPS which can only handle ~ 3 psi. 

   The foam is closed cell and therefore waterproof.  This means that MUCH less care needs to be taken with the foam to
1) Prevent dings
2) Repair a ding when it happens
*There may be NO need to repair dings because the foam will not absorb water. 

   At a full vacuum it is possible to attain the optimal ratio of Fiber to Resin.  This is 60% Fiber and 40% resin. Boeing shoots for 70:30 with its aircraft grade fiber but does so with incredibly high pressures.  The pressure applied during curing is key to both:
     o   Maximum Strength
     o   Lowest Possible weight

   An XPS foam blank can be laminated, built into a board, then torn apart and re-shaped.  This has not been tested, but when skinning the lamination the material surface remains clean, and relatively smooth.  In theory you could take a blank, and remove the rail lamination.  Then ADD or Subtract rail area and re-laminate. 
     o   Think Sustainability
     o   XPS Is also 100% recyclable

   Because the foam is waterproof the lamination layer does NOT need to be waterproof.  Most surfboards have between 2 and 8 lbs of additional lamination, gloss coats and PAINT to seal the EPS (water absorbing foam) from any of 100s of potential pinholes in the structural fiber matrix.  This can ALSO make the board look good.  But the brittleness of these coats MAY also lead to more dings.  And who wants a board that has a 5 lbs dumbbell added for waterproofing when it may not be necessary.
   
See this for a comparison of the foam properties.  There have been some mention of delamination, but there is evidence TOO that this may be a function of

     1) Construction technique (for example using a wet lamination vs. Vacuum bag and
     2) Thermal Insulation. 

The XPS has a boiling point of 160 degrees F.  It is also a better insulator than EPS foam.  Leaving a black surface in the sun, laminated to an extremely effective insulation with a low boiling point WILL melt the foam.  Were working on solutions here. 

https://www.soprema.co.uk/en/article/sopravoice/circular-construction-goes-hand-in-hand-with-xps-insulation?_gl=1*1t2tx9l*_up*MQ..*_ga*MTgyMTY2ODE4OS4xNjc1NjA0MjIy*_ga_XFVVM26VEP*MTY3NTYwNDIyMS4xLjAuMTY3NTYwNDIyMS4wLjAuMA..

Beasho

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #1 on: February 05, 2023, 06:06:30 AM »
This matrix shows the weight of a Board BLANK Only using light EPS (0.88 lbs / ft^3) and standard 1.5 lbs per cubic foot XPS.

Whatever your board weighs ABOVE these weights by liter below is ALL LAMINATION and Hardware.

Meaning a little bit of Fiber, a Lot of Resin and Paint, some fin inserts and handle weight.

XPS is heavier, but with compressive strengths of 20+ PSI you could stand on the material and not ding it (just don't lean on your heals until its laminated).  Meaning the compressive strength is ABOVE what is applied by the average human footprint.  This is NOT the case with EPS and therefore requires MORE lamination layers to distribute the pressure applied by the human foot. 
« Last Edit: February 05, 2023, 06:19:18 AM by Beasho »

Beasho

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #2 on: February 05, 2023, 06:09:48 AM »
Lamination capability:

Because the XPS can handle a FULL vacuum the Carbon fiber lamination comes out looking like this.

I am not sure if this picture will do it justice but the edge, where the fiber meets the foam, is so mashed flat you can barely feel the edge.  This WAS 6 oz per yard of Carbon fiber, which is pretty heavy, wetted out on a table and then vacuumed with FULL Vacuum pressure ~ 22 in HG (~ 90% to full vacuum). 

This pressure would CRUSH the EPS foam, but the XPS no problem and results in a SUPER Smooth lamination.  This finish leaves NO room for sanding because you would just be sanding fiber and a much tighter final weave.  I am not sure how this would ever be possible with EPS because the foam substrate would crush, leaving a looser fiber weave that would naturally result in pinholes.  Pinholes that an XPS construction is now impervious to. 
« Last Edit: February 05, 2023, 06:22:38 AM by Beasho »

surfcowboy

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #3 on: February 05, 2023, 08:31:28 AM »
I appreciate your commitment to lauding this before testing.

Not a single, "we will see how this works." Bold.

 ut know also that we won't troll you if you fail. Thr builders here are all about trying stuff. So if this is an expensive trash pile, recycle it and move on. I've got a dozen spectacular fails under my belt and I'm far behind Pono (though trying.)

I guess I'm saying that for me I don't need to be convinced. If this work we will all likely do it. Or not. But I personally appreciate that you're doing it and sharing it. If this forum software was upgraded I might share more too.

The only question I have is how much water weight goes into those holes. I know nothing will soak in. But my light fabric wetsuit is heavy when wet. My smooth skin jacket isn't. Otherwise yeah it'll work fine. But please try to report apples to apples. Making a board without a handle saves a ton of weight for example.

Also the vacuum stuff is mostly right but Boeing uses prepreg. And you can pull too much of the resin out of carbon on eps if you want. Ask me how I know 😆 I am the king of the overly dry lam.

Keep posting. Can't wait to see what it weighs dry and wet.

PonoBill

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #4 on: February 05, 2023, 12:08:51 PM »
Good stuff. I use a lot of XPS in building stuff, I have managed to crush it a bit with full vacuum, but only where compared to already laminated surfaces (I'm talking about YOU fatboy foil).

Cowboy: I'm a pro at failing as fast as possible. You'll never catch up. Especially since I've automated failing now. Here's my current crop of 3D printed failures.
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.

surfcowboy

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #5 on: February 05, 2023, 09:51:41 PM »
😂 Pono. I'm about to buy a printer to accelerate my chase n

Hdip

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #6 on: February 05, 2023, 10:05:28 PM »
Good Im going to need some shims printed soon.

sflinux

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #7 on: February 06, 2023, 10:19:18 PM »
Where are you sourcing XPS foam?
Quiver Shaped by: Joe Blair, Blane Chambers, Jimmy Lewis, Kirk McGinty, and Bob Pearson.
Me: 195#, 6'2"

Beasho

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #8 on: February 28, 2023, 11:10:56 AM »
We have a problem Batman. 

We have been sourcing this GRAY XPS foam from Whitecap Supply.

The first stock I used was 1.5 lbs / cubic foot.

We bought some more, and I carved out a 26" x 6' 9" board from 2" stock.  The blank came out heavier than expected.  I then re-weighed all the pieces and it is 2.0 lbs / cubic foot.

I have some 1" stock.  Weighed it and it came out at 1.8 lbs / cubic foot.

So the 3 pieces of GRAY XPS from the same supplier:

1) 8' x 24" x 2 " = 1.5 lbs / cubic foot - Original Stock
2) 8' x 26" x 2"  = 2.0 lbs / cubic foot
3) 8' x 26" x 1"  = 1.8 lbs / cubic foot

Since I am targeting to make a lightweight board.  The blank will go from an estimated 6 lbs to 8 lbs with this material that is 33% heavier (going from 1.5 - 2.0).

No Good!  I may run to Home Depot to buy the Foamular which we have confirmed is 1.5 lbs / cubic foot.  BUT you never know.

I will bring my scale to confirm. 

808sup

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #9 on: March 02, 2023, 10:34:52 PM »
Enjoying the experimental build process Beasho. If I read right you used gg to laminate and then bag in some areas of the build. Im probably wrong but I thought I read in another thread that either you or Pono stated gg isnt meant to be waterproof and would expand and fail as water weakens it. Hows the board holding up with pumping up on foil? Any signs of delaminating?

sflinux

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Re: XPS Board Building Advantages vs EPS Foam
« Reply #10 on: March 18, 2023, 08:41:23 AM »
I am a big fan of gorilla glue.  But another product worth considering for working with XPS is Foam Fusion by HotWire Foam Factory.
Head to head tests: Gorilla Glue vs Gorilla Glue Clear vs Foam Fusion:
https://www.youtube.com/watch?v=0Uz9YeehLU4

With scored sections of Foamular, those can be weak points.  Probably better to cut the scored sections and glue them back together.

@808sup: GG isn't waterproof as it is porous because of the bubble formation (open cell like EPS).  The gg will set in 24h, it won't react with water after that so no worry about it loosing strength in a water environment.  But unsealed can take on water like a "sponge" bodyboard.
@beasho: Thanks for sharing your XPS build.  I think Ryan Burch's naked foam EPS Lord Board Planing Hull (0.4 aspect ratio) warrants a revisit with XPS. (As seen in film: Stoked & Broke)  Ryan loved the board but it was fragile.  Has the flex of an alaia, but the paddle power of a modern surfboard.
excerpt @ 1':
https://www.youtube.com/watch?v=Tv150hVVXYg
XPS has more flexural strength than EPS (Ad is misleading as he dropped the first two hammers and gently let go of on the XPS):
https://www.youtube.com/watch?v=-CrK3d4Xke4
« Last Edit: March 18, 2023, 09:19:25 AM by sflinux »
Quiver Shaped by: Joe Blair, Blane Chambers, Jimmy Lewis, Kirk McGinty, and Bob Pearson.
Me: 195#, 6'2"

 


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