2-Sheet XPS Blanks

All input, advice tips received are and will continue to be greatly appreciated.  So far, this thread has been very useful.  I hope more will contribute.

I will post pictures of making the blank for sure.  The board shaped from it may not be worthy of photos.

This is one of many projects in the works and progress will be slow.  Sadly these days, the day job pushes them all to the side too often.  Bonding sheets of foam is the first target.


All input, advice and tips received are and will continue to be greatly appreciated.  So far, this thread has been very useful.  I hope more will contribute.

I will post pictures of making the blank for sure.  The board shaped from it may not be worthy of photos.

This is one of many projects in the works and progress will be slow.  Sadly these days, the day job pushes them all to the side too often.  Bonding sheets of foam is the first target.


Hey BG

Dont give up on this… it can make some great boards.


Heres my favourite board, now 21/2 years old…only one little delam size of a pea… easy fix

it was glassed in 100% woven bamboo cloth still going strong.

The glue I use is Selleys Aquadhere Durabond

heres what off the website it says:


<ul><li>Super Durable</li><li>High Strength</li><li>100% water proof*  – *(not for permanent water immersion)</li><li>Bonds wood to almost anything</li><li>Acid &amp; chemical Resistant – <span class="caps">PVA</span>’s break down with acid/alkaline contact</li><li>Versatile, can be used to bond surfaces other than wood</li><li>Heat resistant up to 140 deg</li><li>Generous working time (10 minutes)</li><li>Expands as it dries</li><li>Sandable – easy, will not clog sandpaper like other <span class="caps">PVA</span> emulsion glues</li><li>Paintable</li><li>Stainable after sanding</li><li>The product is a brown liquid and turns a light yellow when fully cured</li><li>Can be used for gap filling</li><li>Can Also be used to bond surfaces other  than wood I.e metal to  metal</li><li>Bonds <span class="caps">MDF</span></li><li>Non-Toxic (once fully cured)</li></ul>

<h2>Available Sizes</h2>

<ul><li>460mL Easy applicator Bottle</li></ul>


<ul><li>The product is a brown liquid and turns a light yellow (amber) when fully cured.</li></ul>

The way I use it is between 3 sheets (yes 3!) 2 at 25mm thick and top sheet 10mm thick all at different densities.

Doing this way you get the right thickness at the start, less waste and easier shaping … also less tension on the blank as XPS has memory, so less chance of snaping and better flex pattern

Sand the sheets with 40grit before glueing

put first 25mm Dow ND r-tmx sheet pour glue out use a 300mm squeege to spread evenly while using a spray bottle with water until glue has a “dew like” coverage of water

put 2nd 25mm Dow HD r-tmx sheet on top repeat process with glue

then put the 10mm sheet on top and clamp down hard to your rocker table

Glue will foam up massively but most will escape out the side of the blank (which you will cut out when you do your template outline)

This glue is easy to sand and shape!

I have even used it an EPS board as a ding filler (it sucks the water out as it foams up!)

Downside… the colour… but I paint my boards so not an issue for me…

Hope this helps

[img_assist|nid=1066632|title=bamboo xps www.sanded.com.au|desc=|link=none|align=left|width=256|height=160]

Don’t know how long your sheets are, but I only get them 5 ’ long so I use this technique:

The black blocks are 2 sheets of 2 1/2 ’ XPS, blue is the rockerline of your board, hotwired out of the blocks and the red line is where I cut both sheets in a different angle so I can use thinner sheets and get a stronger joint. After hotwiring I glue both parts with epoxy together.


I hope this was understandable and it’s perhaps another method you could use.

This is the way to go for what you want to do . Works good I have done some boards this way as well . You can draw the foil almost to the exact finish shape.

I used 3m spray 77 to put them together . 77 melts foam but if you fog it on  lightly and spray it 24" from you part the solvent will flash before it hits the part.


I forgot to add that when you shape a full sheet without a stringer, it will flex. You’ll need to plan all that out. I’d been shaping stringerless EPS for a while, so the flexing wasn’t something new to deal with. 


People have to learn their own way, but if this was my project I would, make a foil-rocker template, and cut them out of the pieces and then glue them in like a bunch of stringers, heck I would even introduce a stringer or two at that point just for contrast.  Reason being is that is the hardest thing to do in the shaping process is a good foil, so someone with nominal skills could achieve a reasonably pleasing flow with attention to detail.  Still its not my project, so what’s my advice worth anyways?  Shaping that stuff without the right power tools is about the most comical thing I have imagined in a while; not saying it can’t be done well, but there will be a couple of challenges.  I think your up to it; good luck and please post some pictures. X-tune, Hydrofoam, SVF, Javier’s stuff, even the red and blue Dow, i have shaped them all, and in my opinion XPS is the least forgiving and hardest to shape of of any foam type outside of the exotic syntactics.

Hello BgSurfer,

My wife started calling me a surf snob long before I joined Swaylock's. I work right up the street from a nice San Diego reef break that takes most swells. I can't see any good reason to chase blue foam.....but I live in San Diego county....we've got good foam.........

keep track of your time on this project.......time is money...$200 in shipping might not be so bad after all......


Some good input here.  Thanks gents.  I have several options to consider.

Here are a few of the Sways’ threads that inspired me to give XPS foam a try.




(I knew I had seen foam strips in one of the XPS threads sharkcountry.)

i guess i didn’t see (or remember?) this thread before i posted or i would have done so here, but i did a couple of EPS cored with 1/2" blue XPS over top.  i took a different approach by hotwiring foil into the 2 inch thick core layer before bagging the XPS sheets on with PU glue.  i let it set in the rocker jig, and there’s no springback at all on the ones so far.  check out my current  “homemade XPS over EPS blanks” thread for pics.  it was quick and easy.  we’ll have to wait and see how they prove out, but i’m looking to bag some cork/glass skins once i shape them down.  






Link to your thread:


Looks like you’re using the 1.3 pcf (15 psi) Dow Blue residential sheathing.

sure enough.  1/2" blue sheets from lowes over the hotwire-thicknessed 2" EPS, which seems to be ~1 lb/ft^3.  with most of the foil already in-place, the idea is not to hit the core except on the rails.  i had originally thought about gluing on XPS rails, but i’m probably going to avoid that complication.  i intend to full-bag the final board with corecork anyway, so i don’t see much gain.






Use epoxy to bond the sheets together. Put some weight on so you can get some rocker and then hot wire the rocker and thickness after bonded.  Try to make the bond line in such a place that the hot wire won’t hit it.


Thanks for the input.

I just glued up 2 sheets of xps using gorilla glue. The glue bonded to the foam really well, but I didnt use enough clamping pressure and now there are some planar voids along the glueline. 

I just finished squaring up the block and cutting it down the middle to insert my stringer. Once that is in, ill use my hotwire to cut the deck and bottom contours. Once I finish all my shaping, the joint (joining the 2 xps sheets) will be exposed along the rails and bottom of the board, but it wont appear on the deck.

Should I worry about filling in the voids along the glueline between my 2 xps sheets? Im worried that if I just laminate over them, delamination will spread over the whole board.

I could squirt a little PU spray foam into some of the cracks and sanding down the excess once it hardens. Any thoughts?

 I dont care how the board turns out aesthetically and i certainly dont expect it to be perfect in any sense since it is my first one. I just dont want it to delaminate right away.


Hi Hayden,

The cracks in your picture do not seem big enough to warrant spray foam.

If it were mine to do, I would get through stringer, outline, deck bands, bottom bands, and any rough sanding. Stop before final sanding. Now the cracks that matter will be exposed.

Tape off the joint as if you were going to paint a pinline the size of the glue joint. Then go back and use the Goilla Glue and neatly spot fill the open cracks.

Another option would be to get through sanding and do the same tape and fill but with glass microspheres and epoxy resin, peeling off the tape before it all gets too hard…

The annoying part about all of this is that the glue joint usually sands differently than the surrounding foam so one has to be careful not to overdo the rework.

On one of my first boards I cut the outline nose for tail and ended up having to Gorilla Glue the EPS droppings back on to get it right.

Make sure you have a vapor mask (not dust) and/or positive ventilation when hot wiring EPS/XPS especially cutting through those glue joints hich can release cyanides and other stuff.


As Jrandy suggested, I would finish up the shaping before filling gaps between the foam layers.

Another option, other than glass microspheres, might be to mix up XPS foam dust – from sanding/shaping – with epoxy for filling the gaps.

Thanks for the advice.

So I have a few options for what i can use to fill the gaps. Whatever I decide to use, ill tape up the surrounding area to keep it tidy and make trimming easier.

Also I will wear a mask from now on, I wonder how many brain cells have been lost from those few cuts without a mask?

Anyway, thanks for the help.