so this is a kinda weird question, and I’m not sure what the benefits of this would be.
would there be any benifits to mixing foams, such as keeping a XPS core and then doing an EPS shell to give better bonding? I don’t know if the XPS core would have any positive effects, but I thought I would throw it out there.
Tomcat…,
I’ve had the same thought myself.
I’m trying it now.
1/2" EPS over blue dow
let you know how it goes.
also…
glued on 1/8" balsa wood skin over XPS before glassing
Right, not a weird question at all -
Let me throw another semi-weird thought into the mix, though I’ll bet Bill has thought of it already: if your adhesive is okay with both foams ( like for instance a water-based contact cement - http://www.tapplastics.com/shop/product.php?pid=271&PHPSESSID=200510231617451387986648 and similar) , why not use a styrene-resistant outer foam sheet material like Divinycell, not just limiting yourself to styrene-based foams.
See
http://www.fiberglasssupply.com/Product_Catalog/Core_Materials/core_materials.html
and http://diabgroup.com/americas/u_opening/u_home.html
And guess what that lets you do…
I’ve used the water-based contact cements for Formica work and such, easy and cheap. It rolls on with a cheap roller or brush, pretty fair work time for a contact cement.
doc…
Doc,
BINGO ! That’s the whole reason to mix the foams. Getting the best of both worlds. I like the way you THINK.
hmmm, with construction like this you could make like a ig boxy blank and shape it for reall light and dent resistent boards, even make a hollow wood style board but it wouldn’t reall be hollow
Hi Bill,
Oh yeah, stiffer and more impact resistant foam skin that you can use with epoxy…or polyester… especially a flavor that’s pre-scored to bend around 3D curves and goes even better with a little heat application? - I think we have a winner here. Dunno if it’d even need vaccum bagging if you were good with a heat gun.
And I can’t take any credit for this at all - Terry Hendricks turned me on to this stuff years ago.
The idea of using contact cement to hold a core foam and a somewhat denser skin foam together…well, heh, remember Morey’s first boogie board kits? The core and skins that the happy buyer would stick together? Right, well, with the right contact cement, there you have it…
Heh- old dogs can learn new tricks. And they may have a few of their own…
doc…
Doc,
My exposure to Divinycell cross scored foam for compound curves, was through Alan Nelson, around 1980 when he was building his two place composit aircraft, the Dragonfly. Maiden flight was to Oshkosh, and was awarded “Best New Design 1980”. You’re right, some very interesting things could be done with that stuff. I hope someone puts a board together with an EPS core and PU shapable skin, glassed with PE or Isopthalic resin. Swaylocks is an interesting mix of Old Dogs, and Young Pups, inspiration flowing in both directions. Quite enjoyable, eh?
would contact-cement really be an ideal adhesive? it seems the bond is not very rigid, which may or may not be a good thing.
what is the benefit of the XPS coming out of the ends of the EPS on the board posted?
Hi Bill,
Now, talking about Oshkosh and such, that’s something that fascinates me too.
Curious how well the Divinycell, cross scored, is to work with, going around relatively low-radius bends and such. Dunno how shapable it is, say compared to a high-density PU foam, nor how formable the HD polyurethane foam is… but who knows, this could get very interesting indeed… all kinds of combinations are possible. As I am sure you’ve seen, surfboards have been pretty simple tech, and composite foam cores like this could give that so-far-hard-to-get combination of light weight, tunable flexibility/rebound and durability/strength…
Of course, Bert Burger will see this and laugh
Oh yeah, very enjoyable, this is. Actually, the surf biz has gotten awfully boring over the last decade or so, and this is definitely livening it up for me…
Tomcat, a few thoughts-
When bonding a relatively stiff outer skin and a much less stiff/pliable core, contact cement is pretty much ideal. See, what’s gonna happen is the foams will bend and deform differently, such that there is gonna be bending, shear and deforming going on where they meet. Most of the rigid stuff that could be used there, say epoxy or many of the better-grade wood glues, they are gonna crack, bust or break…or break loose, 'cos the foam itself is weak compare to the adhesives and when the foam moves and the adhesive doesn’t, the foam gives way. Kinda like you see on broken boards, where there’s a thin skin of foam still stuck to loose glass - the stuff stuck to the glass but the foam underneath failed.
Contact cement, though, it’ll flex a little and come back, shear a little and come back, the whole thing can move a bit but recover. Makes it pretty much ideal for the purpose.
As to how come there’s blue foam sticking out at the ends of that board…well, I think it’s one of those ‘that’s kinda how it worked out’ deals - like this below
At the top is an approximation of the original glued-together sandwich, seen from the side. At the bottom, that same thing after shaping. Strictly speaking, it’s not exactly the soft-core, dense skin item we’ve been concentrating on, though if the ‘white’ foam used is considerably harder and denser than the blue stuff then you’d get a similar and desirable effect along high impact areas of the deck and bottom with some increased flex at nose and tail which might be good, might be bad…more a matter of tastes than of any ‘ideal’…
hope that’s of use
doc…
Edit: I have no idea where my post went. It was very long & detailed (imagine that, from me!) and had photos too…
I don’t really have time to do it again…so suffice to say that:
d-cell is much stiffer & soaks up much more resin than you think. It has good applications - but use it sparingly.
d-cell holds a shaped edge or an installed finbox much better than lightweight EPS.
Perimeter stringers are your friend.
Foaming PU glue is your very, very good friend. It shapes easily, sets up fast, stays light & flexible, and bonds almost anything to almost anything else.
Boards made with perimeter d-cell stringers are nice; boards with d-cell skins are not so user-friendly.
Not only does the peanut have d-cell rails, but it was fun to make and surfs nice.
The all-d-cell covered board (with glass under & over, like Bert’s first vac thread) well…I think my review was something like “All the weight of a classic pu/pe and all the stiffness & corkiness of a Surftech.”
Thirdly, I did make a bastardized version of a MeeCrafty special - 1# EPS with 1/8" d-cell PU-glued to the deck. Then single 6 oz on the deck & the bottom, and an extra 4" wide 8 oz glass tape layer over the rails to add strength & perimiter weight. No stringer or extra rail foam. I found that ultra-light and ultra-flexible do not add up to ultra-performance in a 10’ noserider (d’oh!)… and now that board is creating good spider habitat behind my garage…
And the experiments continue… 
okay Doc/Bill
I’ll bite and take the challenge…
As I have a 1/2 sheet of 2" blue dow left from my blue rail on lowes foam experiments, I’ll shape the 2" into something wide and low rockered and vacuum (I know I don’t have to with contact cement) on the 1mm woven bamboo skins over the top with contact cement as well as using contact cement to attach some corecel rails. Then glass the whole thing in UV resin.
I’f I have 1/8" corecel I’d use that but the bamboo is alot stiffer than the corecell and doesn’t absorb resin like corecel. Just a bitch to sand the edges…
I was a thinking that since blue dow doesn’t absorb water, a blue foam cored board could support resin/fiberglass free contruction with contact cement and a vaccumed on 1/8"-1/4" cedar wood skin like what Chris Garrett’s building down in Australia for Rasta. The contact cement would provide a protective layer for the foam as you applied the simple sealing oils to the wood like what Garrett’s doing. And water penetration/invasion would not be a problem for the core.
I know that dual layer works already cause Jim Richardson has been doing it for years except he’s using ultra springy polypropelene packing foam around a glassed blue foam spring which is shaped into a board and then coated and sealed with many coats of urethane spray. Kind of like Docs boogie board discussion but with a hard floaty blue foam center… And I have one to prove it.
That’s why I am wondering why everyone here was so eager to dis using blue foam when that’s been the core of all of Jim Richardson’s surflight boards from day one which he spent like 20 years developing. Kind of like Bert and Greg dissing Jim himself which makes me really wonder the motive based on what Bert and Holly and Greg knows about Jim’s expertise in what he’s doing… Read the archives, you can see what Holly had to say about Jim Richardson’s technology. And Holly is supposed to be Greg’s number one epoxy guru…
Sometimes you just got to shake your head…
People here talk about the poly PUPE mentality…
Makes you wonder…
Oneula,
Geevum Brah!
That’s why I am wondering why everyone here was so eager to dis using blue foam when that’s been the core of all of Jim Richardson’s surflight boards from day one which he spent like 20 years developing. Kind of like Bert and Greg dissing Jim himself which makes me really wonder the motive based on what Bert and Holly and Greg knows about Jim’s expertise in what he’s doing…
Huh? What r u implying here? Just curious…
here’s something for ya…take some blue and scratch it with some 36…do the same with eps…now get some epoxy and glass some FG tape strips on each trying to keep both samples equally processed (same glass width and resin amounts). Let that cure for a couple of days and perform some basic peel tests. Let us know what u find.
Maybe the problem is that no one realizes I’m putting wood and other stuff over the blue “before” glassing it so there’s no glass/epoxy contact with the blue. How I attch the woo dto the blue is the challenge but Docs contact cement along with PU glue is an option. EPS would be fine as a skin as well as core/dcell cell but the two both would suck resin like a camel as Benny1 experienced. Treated/sealed balsa or bamboo wouldn’t. The one thing people don’t understand is that CMP’s technique is all about skinning the foam, any kind of foam with balsa. Epoxy and EPS are just options, he never used the stuff until recently so mostly it was all wood over regularly shaped PuPe foam. What you glassed the outside with was your choice. The wood skin allowed that.
Benny1 knows if you don’t sand the surface coating off this bamboo cr*p even epoxy will will bead up and slide off the material…
Greg once said here that you should never plan on making a board from blue XPS and sell it to someone else, Bert pretty much said the same thing. What they are telling me is Jim Richardson is selling a lie and ripping people off with his Surflight boards. It’s as plain as black and white to me… So is he or is he not perpetuating a fraud like Bert and Greg are saying?
Personally I don’t believe so, and if Holly’s little sunset story to CMP in the “Death to all Dairy Workers” thread wasn’t a bunch of BS then he doesn’t believe Jim’s product is BS either… Holly know what Jim is doing as well as Bert and Greg and they all know who’s supplying who with Holly’s tech.
Two things that recently caught my attention about blue…
The first was that I gorilla glued blue rails to .75lb EPS foam in a bag. When I opened the bag you should seen the water pour out of the bag from the sponge bath we gave then foam to activate the glue. Funny thing in that never happened with the EPS glue up. So I wonder where the water went with those blanks? hmmm
The second was we’ve had some of the worst rain storms this past month or so here in paradise. Kauai guys ate it worse, but yesterday in Ewa Beach we got like 5" of rain and a hell of alot of flooding. I had to run all the stupid EPS sitting out back under the patio tent into the garage to prevent then getting waterlogged. Left blue panel if the torrent cause water and it just don’t get along. You could shoot it all day with a water hose and it won’t make a difference.
So I ask myself is that something I would want as a core under my prefab wood skins even if the wood wasn’t completely attached to it versus PU or that beaded EPS foam? Seems like it…
Unfortunately unless I make it super thick or super strong it sounds like she’s gonna snap.
So then why is Jim Richardson wrapping his Blue foam cores in soft boogie board material?
None of it is making any sense.
What BS here is the real BS, that’s the quandry…
Kind of glad my retirement is coming up soon…
I’ll do a couple for the boys though before I chuck it all.
Greg once said here that you should never plan on making a board from blue XPS and sell it to someone else, Bert pretty much said the same thing. What they are telling me is Jim Richardson is selling a lie and ripping people off with his Surflight boards. It’s as plain as black and white to me… So is he or is he not perpetuating a fraud like Bert and Greg are saying?
Ahh, thats what I thought. Unfortunately your comparing apples to oranges. Too bad JR isnt here to offer his 11 secret herbs and spices. HA!
What Greg and Bert are suggesting is just plain old shape and glass approach to blue…what JR is doing is light years ahead.
Plus…hmm, think I’ll borrow one from Doc…take an egg and wrap it encase it with some of that viscoelastic memory foam they use for matresses (btw, dont sleep on that shit unless you got a death wish)…now drop it on the floor…egg wont break.
Anyone can make a blue…but when Greg says dont try to make a living off it, its sage advice…and free, no extra charge!
Take a sabatical bruddah…if and when you come back it’ll be enjoyable again.
Looks like Salomon is buckin the trend eh?
Oh and btw, if I were betting on it, I’d say he’s not using epoxy to bond the blue laminate to the blue foam…there are many options that can be used to attach a laminate to a core foam material…including pu adhesives which work great on blue…proly the same stuff he’s using as a final coat.
http://www.sashcosealants.com/home_improvement/products/throughtheroof.shtml
Something like this stuff that stays flexible might be good for a skin to xps connection.
Although a lot of people who’s opinions I’d have to defer to have said no-go on the XPS I’m interested in it because I have a pile of 2" and 4" XPS left over from various construction projects to play with.