VÆSKE,
Who do you buy your foam from?
from a small business guy in a warehouse in Denver. ‘Foam Form’. He only carries EPS 1 lb, 1.5, 2 & 3 lb blocks, gotta buy a full block @ 3’x4’x8’. ACH can produce 16’ blocks and this guy can special order them.
We can’t buy PU foam in Colorado unless you get something shipped in from US Blanks. With shipping, might as well build your own blank. When I was in SoCal, I bought blanks from Foam EZ, I lived 15 minutes from Westminster. learned with PU.
Hey nj_surfer, curious if the micro (or foam dust + epoxy (minus additive F) method is a sure-fire seal coat/waterproofer that pretty much eliminates this seepage concern at the skin level of the board? -I did one of these seal coats in epoxy and noticed my foam was getting attacked; the culprit was the F. So, for seal coats w/epoxy (coupled with easy sanding), I resort to micros. …maybe I was using too much F.
EDIT:…that said: if this foam doesn’t suck in water, we can assume it won;t suck in epoxy that’s for damn sure. So why would we be seal coating this unicorn EPS?
Marko iFoam
almost impossible to get with out connections
but doesn’t suck water
polypropelene/polystyrene special mix so you can shape it.
I think they make those Catch Y-surfboards with Polypropelene
personally i like the blue dow extruded polystryrene not the expanded polystyrene
I once shot a water hose at full blast on it for a long time with no penetration
feels like a creamsicle shaping it and i like its “ping” sound when plucked
but with no gap for the burst bubble gas to escape it can be a challenge unless done and handled right.
cool, but this “connections” foam is actaully stocked in big blocks in a no-name warehouse I buy locally in my state. It’s the real deal as far as I can tell. Like I was saying to nj_surfer: no need to slurry spackle on these shapes because if the foam doesn’t suck in water, it sure as hell won’t suck in epoxy. My build method now is sand to 100 grit and glass and be done with it. Too easy.
I was given a couple of these blanks for my sons. Stretch uses these blanks sometimes. It’s not easy to handshape: it gets a bit fluffy and it’s dense. Stretch suggested getting it machine cut to minimize the amount of handshaping. He suggested using a disc sander to shape it. I’m not good enough to do that.
Marko has been advertising machine cuts on their Facebook page. It sounds like they are willing to deal to the nobodies.
At Stretch’s suggestion, I let my son ride it without glass. I weighed it prior (3.1 lbs) and after (3.5 lbs). After a few days, it was still 3.5 lbs. I think the extra weight is from the sand in the pores of the blank.
Can you suck air through the foam?
I’m guessing it’s ACH Geofoam we are talking about here. ACH claim max 2% water absorption by volume for the 2.5lbft3 version.
On a 1 liter (10x10x10cm ~ 2.5x2.5x2.5") test piece you’d expect 20 ml of water to be absorbed = 20 grams (0.7 oz) MAX
On a 34 liter board (a big boy 6’6") 2% volume would be 0.64 liters = approx 640 grams of water ~ 1.4 lbs MAX
After working with a few local Aus suppliers of EPS to try to get a less porous foam the conclusion their experts came to was that they could not achieve high density “fused” foam in large billets (typically they blow foam 4.8mx1.2mx600mm about 16’x4’x2’).
Their input was that low porosity EPS foam could be achieved in smaller billets and that’s how the blank guys are getting such low porosity. But maybe they simply didn’t know.
Nope, can’t suck air though it or blow air out of it. It’s wild stuff. I cut a sliver section about 1cm thick and tried pushing air through it, no dice. In the thread is pretty much verbatim of the numbers you put up there, also some vacuum and water tests done too. Was on the phone with a tech today at ACH, got the junkett. Nice flex too. I took a 3" thick billet and bent my rocker line with glass scraps and resin for a stringerless 1.5lb shape instead of hot-wiring the rocker out. Fun to work with too.
I personally favor Abranets for all EPS. FoamEZ started selling their stuff with a proprietary pad; does a slick job. The course nets are radom patterns and as you increase grit, the texture on the net gets real squiggly, and the rail jobs are like butta. Sometimes I think I’m looking at poly blank when I walk out of the shape room.
I use a AU Shaper’s gold grit drum on my Skil. I paid an arm & leg for this thing, it struggles on big stringers, or maybe my tecknique blows. Otherwise, the grit drums are a nice sand into the EPS blank. But I don’t really notice the diff by the time I get to the hand work…I bought that drum for long 14’ mows on racing hulls.
Waterproof eps doesn’t exist. I repair all kind of eps boards and i find water in surftech and molded (usblank and marko) eps blank like other foam.
My eps supplier make immersion test and show that is foam take less than 2% of water by weight. I do the vacuum test with sucsess. But when this foam is in a board that’s ding it’s suck water. Pu in board suck too but less. The good think with eps it’s easy to push water out with pressure air (i use a hand pump for bike wheel). Eps is not affected by water, salt is more a problem if water stay in foam.
Sorry for my frenglish.
marko ifoam is way different to shape than regular eps. instead of shrinking when you sand it just gets furry and stops shrinking, you need to plane and plane it down and not rely on sanding.
yep, we clarified that through the course of the thread, sorry for the topic title being misleading–I was definitely misled by other board manufacturers claiming ‘waterproof EPS’. They need to act rite, and state like it is. “Virtually Waterproof” is Surftech’s lingo. Next time a customer asks me if this thing is waterproof, my asnwer is “maybe”.
you need to apply an internal springer or perimeter stringer to hold the rocker before shaping the profile
we usually cut a rough outline 1-2" inside the normal outline and apply a perimeter stringer of HD foam or wood or wood/cork or foam cork mix to hold the rocker in place once that’s set you can hack away all you want and not worry
usually I’ll apply a thin (1/8"-1/16") layer of wood(paulownia, balsa, cedar, redwood and then a layer of blue dow or wood and cork on the outside of that to prevent water intrusion from rail shatters. Italso puts the hiigher density/weight out on the rail. You’re normally doing this on PU anywy with the lappinng of the cloth layers
If you inset a good sized horizontal springer while bending in a rocker between the layers it’ll keep the rocker as well.
many years ago around 2005-2006 I gave CMP a home made blank with just an internal horizontal woven bamboo springer and he kept it for 2 years before shaping it and it didn’t lose its rocker.Turned out to make a pretty bulletproof board in the end from what he told me.
RE the forced rocker. I did this last week, glassing two sheets together, but then as I cut the fibreglass the rocker flattened out. Duh! Will you just shape without cutting into the fibreglass strip?
I’ve just started to glue up 12 x 2" rocker profiles cut from a sheet of insulation foam to see whether that works out better.
Did ACH give you any hints why their EPS is non porous or what they do differently?
ACH didn’t give me insight to how they make their stryo, but there’s some interesting clues someone threw up on the boards, something about they decrese the size of the expanded block and it creates a more compacted fused foam. All I know is this is not your dad’s stryo. It’s killer. I’m assuming it’ll surf great. Works good on flatwater, resin stiicks to it. Good times.
RE forced rocker: Oneula’s method is basically adding a parabolic to hold it’s rocker now that I read it again. The reasons I bend a raw billet 1) I’m cheap and want to bend the 3" billet instead of wire it from a 6" block, I save enough foam for another baord, so there’s incentive. 2) I don’t add a wood or foam parabolic, instead I use a glass/carbon combo tape for my parabolic, I don’t run it tip to tail, like 2/3rds.
I lay the billet in the sun, warm it up. I cut 1/2" x 1/2" slits along the bar line, then I bend it a couple times. I mix up some resin and scrap glass, layer up a matrix, visqueen it, then bend the rocker. Let it cure overnight. Shape the deck ass-backwards, get the deck dialed and turn your rails. What I do is dial in the rails and leave the bottom middle proud w/the matrix intact. I take the matrix out last with a power pad and 40 grit. But after the deck’s been glassed–or after the parabolic tape is cured.
Interesting. That’s the feedback we got. Smaller billets and you can get better fusion.
one last note I need to correct myslef: can’t just glass on this foam unsealed with add Additive F, it’ll attack the foam. epoxy and micros or spackle is still best so you don’t deform your shape during the lam cure. A touch of F might not do anything, I tend to use more F… I get pits sometimes after my final screen, might as well do it right and mirco ballon the blank.
1% Add F won’t effect the foam. But if your sealing we don’t use F in that. If your airbrushing the paint will bead up.
thanks greg
One problem might be that the standard test used may not show accurate water absorbation either. According to the website of one of the local EPS makers, their billets absorb 2-4% water by volume after 28 days of submerging. However in the brief for the test standard used (ns-en 12087) it’s stated “The long-term water absorption by total immersion is not directly related to the conditions on site, but has been recognized as a relevant condition of test for some products in some applications.” So basically the water absorbation rate is a rating used to compare products, and can not be counted on as the actual absorbation. For a good way to measure water absorbation for surfboard application in a lab, I would take a block of foam 4"x4"x10" and seal it on all sides, then cut a two inch hole in the bottom. When submerged, an actuator would compress it 1/4" every 3 seconds. Leave that for a month and see how that comes out. A more practical approch might be to just shape it and cut a 2" hole in the bottom, weight it and surf it for a month, then reweight. Thing is, even with a low water absorbation like 1% for a 2.5kg board of 20 liters the water absorbation of 200g is an 8% weight gain, which might be significant and noticable. 2-4% water absorbation most certainly is. And then the question is what the actual water absorbation is. Here is a table which show water absorbation of sample of 180 measurments of EPS which have been submerged for “up to 12 years”. Horizontal axis is depth under soil, vertical is water absorbation percentage. Black graph is well drained area, purple graph periodically submerged EPS and the green graph is in undrained soil.