Even if there were two holes or more, if the ruptured cells are not near any holes the expanded gas(be it pentane or air or a mix) can’t release through a vent hole, as it can not get there. XPS is a closed cell foam, gas cannot pass through it…
I just can’t see how vent pin holes can work (unless they are all over the board a few mm apart, which doesn’t seem feasable)
Thats a really good questions! Its a closed cell system wright, but the whole gas go out of the foam, so something must happend in the foam!?
I have made also just the things that surfding has written in his post + made some pinholes (not on the glassing!!) on the foam for a better adhesion. iam cheerful spirits that this will work!
@surfding! You have seen my iced places around the board! I guess that these are air bubbles! Can i put some resin on the blank before i lay down the layer on the blank to prevent the air bubbles?
hey christoph,
i think that crytalization is due to the resin not bonding to the foam. This is caused, as Sd pointed out, by too much paint, or in some cases, incompatible paint.
The way around this is to use only enough paint to give the color, and make sure it is acrylic or tempera(called poster paint in the UK). That way the resin has a chance to bond with, or through the paint to the blank.
If you cheater coat over the paint, you will have to find a way to key into that - sanding, etc… - so that you don;t end up with delam later.
As far as pinholes go, someone pointed out that they have to be within 1/2" from each other to be useful.
I think the idea of glassing the bottom, then baking somehow so the gas exits via the deck is the key. If you get the gas to exit through the deck before glassing, you will eliminate that happening after it is glassed, and if denting occurs.
At least that’s how it happens in my head…
I have a friend who is a scientist who told me that the problem is not delamination but shearing. It’s a separation of the glass from the foam. that’s why I leave it them rough (60 Grit).
I would rather use NOVO paint on the hotcoat after sanding. Then use a Automotive or Marine Clear. Then polish or Matte finish it. I never spray directly to the XPS however I have board builder friends that do. They use Tempera evenly sprayed. Even on PU you can get Catalizing if you use the wrong paint or too much.
Christophe just finish your board and ride it. Work out the details on the next one. Don’t expect to make retail quality your first go at it. You should be stoked you got this far! To make an XPS your first round is pretty impressive. You must have Elephant BALLS!!!
I got slam with board orders today so I have a lot of Shaping to get done.
Well back to the grind!!
I don’t do pin holes! I like your illustration.
100% true! that’s why my board broke. The lam separated from the deck, but the foam/stringer were still intact 
I have to mention that the rails broke first and because I did not care about that, my deck separated after a while. That’s why I still believe there is a lot of strength in the rails, especially with XPS boards (where the bonding of the lam isn’t that good). But I still blame the poor lam I did, with 3x5oz top and bottom the board should have been bulletproof.
The reason why I did not care about the breaking rail: I wanted a new and better board 
The board is now a wall hanger. (It’s the blue shortboard you can see on the first page, it served me 4 years)
“If you cheater coat over the paint, you will have to find a way to key into that - sanding, etc… - so that you don;t end up with delam later”
I mean i will cover the foam with a little bit resin, after 5 min i will lay the layer down and glass it normal!
Just to secure, that all places are covered with resin!
P.S. I used normal dispersion paint for the blank
@surfding: you are wright, like every time;)
it served me 4 years
If it was PU it would fell apart in less than one year. Plus PU losses it’s live rather quickly whereas the XPS has memory/
Hey SD! Why don’t we do it on one of the 800 of them that I got from you! LOL
I have acces to a high def camera and the whole deal.
One of your shapes…or one of mine…makes me no difference!
It could be the “Synergy Ward”!!! (you know…like a “hospital ward”)
What do you think?
if its the ward with shrinks in it i want to see pics!
“Mental Ward” …wait…that’s my home! lol
SD…Were the blue extruded ones I got from you with stringers done the way you outline here? Lemme know.
If you want to do one together and take the pics that cool with me. You have seen my kid surf. Let’s use one of his models so he can be the test pilot.
I’m real picky about the surfing part!
SD
Remember in the Mental Ward I’m the Shrink!
You can have the couch! LOL!!!
Hey Dead:
Did you get some of the XPS when you cleaned me out of all my blanks last year?
I guess you must have. It’s really cool stuff. Your so good at laminating it will be a breeze for you.
Looks like I’m going to do another round of boards in XPS. Some of the Pro’s want to revisit it.
They like the springyness of it. It’s alive!!!
SD
Forget the couch…you have to break out the jacket for me! lol
LET’S DO IT!
Let me know when.
Did you guys ever build/document that XPS board? I'm just looking for some inspiration...
I will revisit all projects in September: XPS with a special cloth. It's a new technology that I need to prove before making any claims?
Photo's will follow however not until September.
ok. Sanding the bank is enough but…why xtr surfboards use that expensive technology then??? Does somebody know what they are doing? dings…we just said that it doens’t work (gas can’t move in the blank).
I shaped one some years ago (vacuum and unidirectional carbon reinforcements) and i had some small delams after some months.
Some friends don’t vacuum them because they thing the exces of resin can help to prevent the delams. In the vacuum (excess goes away). Expert people like surfding uses vacuum almost 100% without any problem. The no vacuum theory looks valid too: sanding (40-60 grit) and flling that space between the blank and the fiber with more resin. Who is right???
Can it be better to prevent delams if we glass the first layer with 2-3 oz instead of 4-6 oz?
I’m not an expert in this kind of blanks…maibe expert people know the answers. thanks
Since I am MUCH closer to you now SD I really want to be involved in this project.
I’m now in Culver City right near the 405…about 15 minutes away!(maybe 20)
Actually…I think I wanna come hang out with you this week if that’s cool.
Talk soon!!!
@ Jeffleppard: Tell me what kind of inspiration do you need:)?
@Jellyfish.....: What do you mean with: why xtr surfboards use that expensive technology then? What are they using? I think you mean the marketing strategy similar to BUFO:)
Believe me the gas isnt the problem! I have talked to some producers of XPS here in Germany, they told me, that the gas leave the XPS during 90 days completly!
"Who is right???" ==> SD is always right;) I have shaped two XPS boards without stringer, i have just followed the instruction of SD, no problems at all:) (THX again;))