drewtang , im going to except that reasoning as a valid argument , because ive used similar comments in the past …
so i guess we wait and see …
pinhead !! the polyethylene nonstick isnt the only problem …
when you do peel tests , you get a fine layer of foam stuck to the glass , so there is a bond to the foam …
even tho the foam can flex , its cell structure makes it rigid at a micro level …
its this rigidity that creates poor overall shear properties …
so as soon as you pressure dent it or create a local stress , the bond to the foam will be greater than the bond to itself …
its pretty easy to test the principle …
go and get a chocolate covered marshmallow bar of some description …
then go get a chocalate covered honeycomb bar …
now try and peel the chocolate off both ???
both will have a similar bond at the surface , but the substrate will be the difference as to which one has greater peel strength and resistence …
limiting flex is a key to maximising the use of this foam …
it starts to fall back into the realm of urethane , im not writing this stuff off completly , but if you want to push the limits of strength to weight , then this isnt the answer , but if your satisfied to make a general surfboard with similar properties to urethane except using epoxy instead of polyester , than its an option …
the life expectancy even with use would outlast a urethane board of similar weight , as long as you watch the extreme heat …
the gasing problem is only inherent in surfboards and not insulation …
the poor shear properties means when a cell is broken due to stress , its contents are free, which when combined with the gas from other broken cells form a pocket , this pocket is the wedge , like a small bubble under a sticker on a hot day , it expands , but a sticker only has the small amount of air it started with so only grows so far , XPS will gain more as the bubble grows because as it grows it breaks more cells …
insulation isnt getting pounded and flexed , creating stress , insulation isnt sealed under a layer of glass …
even making the little holes in the glass job , will eliminate the growth of a delam , but it wont stop breakdown due to stress associated with flexing and pounding under the feet …
but the bottom line is , if a superlight urethane blank with a 4oz glass job is exceptable , then so would this stuff be …
for a urethane board builder looking for a fill in , its an option …
but if you were going to use blue XPS dow and epoxy , you might as well use 2.5 lb eps and epoxy …
youll have way better strength and durability , a larger range of flex before problems , its white …
both require extra effort to make , i would choose the one which kept me in business , this time for many , falling back to clark isnt an option , like the last time many made a foray into XPS …
regards
BERT