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General => The Shape Shack => Topic started by: Beasho on February 05, 2023, 06:00:12 AM

Title: XPS Board Building Advantages vs EPS Foam
Post by: Beasho 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 100’s 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.  We’re 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..
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: Beasho 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. 
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: Beasho 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. 
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: surfcowboy 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.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: PonoBill 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.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: surfcowboy on February 05, 2023, 09:51:41 PM
😂 Pono. I'm about to buy a printer to accelerate my chase n
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: Hdip on February 05, 2023, 10:05:28 PM
Good I’m going to need some shims printed soon.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: sflinux on February 06, 2023, 10:19:18 PM
Where are you sourcing XPS foam?
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: Beasho 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. 
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: 808sup 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. I’m probably wrong but I thought I read in another thread that either you or Pono stated gg isn’t meant to be waterproof and would expand and fail as water weakens it. How’s the board holding up with pumping up on foil? Any signs of delaminating?
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: sflinux 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 (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 (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 (https://www.youtube.com/watch?v=-CrK3d4Xke4)
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: juandesooka on August 08, 2023, 10:43:29 AM
Toying with idea of an experimental XPS build.  Sounds like the question isn't if they will delam but when.   

For those who went there ... how did it work out after some use?  Not out of the bag looking sexy as heck, but after 6 months or a year of dozens of sessions in varied conditions. Hold up decent? Or steadily failed towards a disappointing end?
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: clay on August 08, 2023, 01:34:31 PM
Appletree has been making waterproof boards for a number of years, have yet to hear of any reports of delam.

My xps wing board is going on 4 months old, at least 40 sessions to as many as 80.  I have been rough with her and no signs of delam or failure.  A month or so ago I drilled a 1 inch hole in the deck to the bottom for a camera pole, once I pushed the pole in so far it pushed some of the skin away from the bottom of the board.  If anything was going to delam the board it should have been that.  I have since put some duck tape over the hole and kept riding it as is, no sign of delam or failure.

Van was in the shop for 6 weeks and I was throwing the board in the bed of a pick up truck with some wood scraps with bolts sticking out of them.  I would be terrified of doing that with an eps board.

Maybe I have just been lucky so far, and it is going to fail any day now.  My xps sup foil board is older with fewer sessions and it looks good as the day I finished it.  We will see over the next year how she looks.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: surfcowboy on August 08, 2023, 07:45:57 PM
I'd expect XPS boards to delam more likely if they are sealed. I'm betting these are a bit more "ventilated" at least as Beasho does it. So there's no pressure to delam it.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: juandesooka on August 09, 2023, 08:44:59 AM
Appletree has been making waterproof boards for a number of years, have yet to hear of any reports of delam.

...

Maybe I have just been lucky so far, and it is going to fail any day now.  My xps sup foil board is older with fewer sessions and it looks good as the day I finished it.  We will see over the next year how she looks.

Thanks Clay. Are these DIYs?  Or Appletree?  If DIY, what system did you use for lay up?

If Appletree, the worry remains that they have figured out some secret sauce to make this work. Maybe some variation on xps that is less resistant to resin, or some clever trick to make it stick.  As they appear to be the industry leader in this, the only company mass producing these boards. Other than a few experiment posts here and there, like this thread, seems like builders give it a go, then give up.  So before I start, I am seeking some more info on home build success....did they all fail after a few months of use and it was easier to go back to tried and true eps (with its flaws), or maybe they are so successful that no more boards need to be made, board-for-life?  :-)
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: StellaBlu on August 09, 2023, 09:23:41 AM
Worth listening to a few of the podcast interviews with Weiger from Appletree.  As someone with very limited knowledge of board construction other than repairing boards (but having listened to said interviews), my understanding is that the "secret sauce" has something to do with their vacuum technique and how it bonds the skin to the XPS blank. How it differs from a normal vacuum process goes a little bit over my head, and they are somewhat opaque with the details, but I'm sure someone with more knowledge could get some hints from these interviews.

I don't think the foam differs from standard XPS.  Appletree packs all of their boards with excess foam cuttings, so if you want to inspect their foam to determine whether its normal XPS or something different, see if you can find someone receiving a board from them.  It is very dense and stiff foam.  It can carry a LOT of weight without flexing and when it fails (which is hard to do) it just snaps. 

I punctured the skin on one Appletree board, but they have clearly changed construction since then.  Another board suffered a big ding on the corner during travel, and I had to remove some of the skin and foam, which was extremely dense and well bonded to the skin.  They aren't as indestructible as others make them seem - the bigger difference is that they never seem to lose stiffness, and they don't need to be patched immediately if you do ding them.  Their new in-house tracks are also VERY solid.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: PonoBill on August 09, 2023, 01:32:49 PM
I think XPS delams BECAUSE it's waterproof. EPS boards equalize the pressure of water vapor throughout the board. Water vapor in an XPS board has nowhere to go.  That's why vents work on EPS boards. They don't work on XPS boards because the air can't move around inside the board. I've vacuum-bagged XPS a lot, and while a full vacuum will crush and deform the XPS a little, it's nothing like EPS which crushes down to a wad of plastic. I've never had problems laminating onto XPS as long as the surface is prepped (coarsely sanded).
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: juandesooka on August 09, 2023, 04:03:19 PM
I think XPS delams BECAUSE it's waterproof. EPS boards equalize the pressure of water vapor throughout the board. Water vapor in an XPS board has nowhere to go.  That's why vents work on EPS boards. They don't work on XPS boards because the air can't move around inside the board. I've vacuum-bagged XPS a lot, and while a full vacuum will crush and deform the XPS a little, it's nothing like EPS which crushes down to a wad of plastic. I've never had problems laminating onto XPS as long as the surface is prepped (coarsely sanded).

Do you have strategies for managing this ventilation, to allow vapour to escape?

[and because no like or thanks button on this forum s/w,  thank you Stella Blue for reply too]
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: PonoBill on August 09, 2023, 08:25:10 PM
Probably the best strategy is don't hotcoat. In fact do the opposite--make sure any lamination is super sparse on epoxy--enough so that any trapped gas can escape through the surface. The things I've made with XPS didn't go in the water, except for a handplane.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: Hdip on August 09, 2023, 08:45:17 PM
Did someone mention off cuts? 😀 new toy in case the wind ever comes back. Omen 60l which I’ll be using for winging. I’ve gotta say. Their packaging is really impressive. The foils came in a box so pretty I had to save the box.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: StellaBlu on August 10, 2023, 06:25:17 AM
Did someone mention off cuts? 😀 new toy in case the wind ever comes back. Omen 60l which I’ll be using for winging. I’ve gotta say. Their packaging is really impressive. The foils came in a box so pretty I had to save the box.

Dying to hear how you like that Flux.  Im considering the 48L to replace my daily driver (Apple Slice v2 60L).

Re: the cuttings - those cuttings (green) are different than all my other Appletree cuttings (white).  Also, all of the Appletree boards I have recieved from the factory (including this year) are packaged in the full cuttings from the blank in a single piece (board nestles right into the donut hole from the rectangular blank).  Point being - Im not totally sure whether those cuttings are from the blank or not.  Maybe they are doing something different for the Omen boards.  Im sure your packaging was lighter to ship than what I've had in the past.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: Hdip on August 10, 2023, 08:08:22 AM
Interesting. I have the 4'3" 36L and really like it. I've come off of 4'5" and 4'6"s in the 27-31L range. The Omen 36L feels longer than any of the other boards somehow, but does a better snap turn than my older boards, and can hold on a rail turn when needed.

Very excited to get the wing board in the water. Which of course means there's no wind anywhere in the forecast.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: surfcowboy on August 12, 2023, 07:57:01 AM
Pono called it. Delams are caused by the skin blowing up like a balloon. Carbon when bagged and filled lightly, which means about as good as any home guy can do is full of pinholes. That's should vent you fine. And if you laminate anything with a bag and the blank is coarse sanded it'll be stuck down well so not much water will get in and since the foam doesn't absorb it'll just dry when you get out.

Clay and Beasho are showing a new and likely better way to make foil boards. I've maintained for 2+ years now that these are not surfboards. They are tools for getting on foil. We gotta stop trying to polish them like a longboard and we need to ignore all the surf dogma and make what works.

Go build one. I'm trying to work out sourcing XPS myself.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: PonoBill on August 12, 2023, 07:44:59 PM
Home Depot XPS is just fine. In fact, the quality is better than some of the "surfboard" XPS I bought. I think it's challenging to make XPS that is homogeneous. Some of the stuff I played with had areas that probably didn't foam well and had the consistency (and weight) of PVC. the pink insulation is perfectly homogenous. The only problem is that it's scored to break. Some folks break it and glue it back together with good foam glue (regular Gorilla Glue is NOT Da Kine. The clear non-foaming GG is better, but specialty foam welding stuff is WAY better). But really, once it's laminated, the scoring doesn't matter. I just use it as is. I'm getting ready to buy a silly quantity because I want to build an ultra-light trailer for my dirt bikes (yea! another project), and I'm going to use XPS to make a streamlined body. Towing behind a Tesla has special requirements. I've been fiddling and I have my ordinary modified trailer tuned up so it only cuts mileage by 20 percent. I'm aiming for nada.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: surfcowboy on August 13, 2023, 04:02:27 PM
Pono, I wished we lived closer together. I literally have a YouTube feed filled with foam walled camper trailers.

Good to know about the Home Depot foam. It was constrained here for a bit but I saw the 2" thick back at some locations. Just gotta look around. Also a good tip about the other foam glue. I have some good prop house supply places near here and they have tons of that kind of stuff. Didn't know it was superior. Thx.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: seastudent on August 14, 2023, 07:33:31 AM
Also you can get 3" thick at home depot. I'm fiddling around with a board at 7'6'' x 22" and got it out of 1 sheet.
 Bill, could you give some guidance on rough sanding? I kind of smoothed mine out to 120 grit to help my eye and hands find my many, many flaws. I can certainly roughen it back up.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: PonoBill on August 14, 2023, 05:23:56 PM
I do a once-over with 40 grit. Very light pressure--you just need to scratch it up
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: clay on August 14, 2023, 06:41:38 PM
My boards are diy builds.  We had Jeff's 2 year old prototype as the model for what might work, and then Denton got all scientific and did tests and came up with a glassing schedule.  So we ran with that and our own best guesses.
I made a full tutorial of my wing board build:
https://clayisland.com/how-to-make-a-waterproof-wing-foil-board-video-tutorial-from-start-to-finish/
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: clay on August 14, 2023, 06:43:31 PM
short version:

https://www.youtube.com/watch?v=1VH80tkG8R4
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: juandesooka on October 20, 2023, 12:57:18 PM
anyone experimented or heard anything boarding shaping using graphite polystyrene (GPS) foam?
https://www.progressivefoam.com/eps-vs-xps-vs-gps/

Is it more like EPS or XPS? Appears to  have more moisture retention, which is bad (when board inevitably gets dinged) and maybe slightly good (perhaps improves on the resin absorption / delam issues with xps).

Apparently this is the most common rigid insulation in Europe. I am curious if this may be related to Appletree's proprietary closed cell foam.

This all flows from my looking for 4" thick sheets of xps, unsuccessfully so far -- shows they make them, but out of stock.  A friend in the green home biz recommended checking out gps.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: blackeye on December 03, 2023, 11:42:48 AM
I think XPS delams BECAUSE it's waterproof. <snip> Water vapor in an XPS board has nowhere to go. 


This would have to be water that is sealed in after a repair, or perhaps condensation from ambient moisture in original construction? Beasho's theory is that water intrusion will just find its way out the way it came in.

My very old very amateur very beat up paddle blade with XPS is sound. I used the coarse surface sanding method.

I'm wondering whether the resin/foam interface fails or is the failure foam/foam beneath the resin that causes the delamination experienced with XPS? I am aware of 80's boats that delaminated because the two skin layers ground down the core between them.

Also, there was discussion years ago about XPS and the mold release on its surface.
Title: Re: XPS Board Building Advantages vs EPS Foam
Post by: lazymodo on February 24, 2024, 02:11:05 PM
My experience with XPS has been that over time it expands and swells.
I used it for box inserts within 1lb and 2 lb eps and in all cases it swelled and raised abouve thoe original shape (EPS remained stable). My guess is that the blowing agent that normally escapes EPS when it heats is trapped within the closed cells and still expnds with heat but cant escape the closed cell structure.
Just my expeirence.
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