EPS Boards

[sinistapenguin]

Hi All

OK - I'm getting confused here, so I was hoping you guys can clear it up.

As far as I can see EPS is just another foam. Traditionally you'd use a Clark Foam blank and glass it up. Presumably therefore, exact materials aside, if you get an EPS blank, you can still shape it in the same way and glass it up yourself?

I get the idea that the blanks are pressure moulded rather than cut and sanded, but that doesn't mean you can't change the shape - presumably you can sand the rails to change them/ alter the shape a bit?

Then you don't have to coat them in plastic as NSP etc do, but you can glass them and essentially have an EPS custom board rather than a pop-out?

Am I right?

Sinista

[grub]

Yer, confused as I don't know much about Expanded Polystyrene (EPS)...

I have the feeling that it is much harder to work with... noting that the density is much less and the outer surface finish of much lower quality... I am also wondering how the chemical formula of EPS reacts to the std. polyester resine??? I really have no idea on this subject and would like a bit more info too.
___________________

"its more important to understand than to be understood"

[drowningbitbybit]

It's all gonna get more complicated now Clark have gone...

Essentially, Sins, you're right

There are some differences between exact type of EPS and manufacturer though - how much 'hand finishing' goes into it varies from one board construction to another.

Generally though, the 'blanks' are pressure moulded to an exact set of specifications, then finished off by hand.

A description can be found here...

www.surftech.com/tuflite.php


As for the standard polyester resin - yes, you can repair dings with a standard ding repair kit.

[Dopey]

[tomcat360]

it seems that the EPS i worked with for a skate mold wasnt too bad, but it tended to tear more than cut. I used hand tools, except a finishing sander. it makes a huge mess, or for me it did. what happens is when I was using the surform all the little particles cut off and get staticy-ized. then it sticks to everything. my entire house had a very thin coat of pink junk.

I really dont know how it would finish. you can go get some EPS insulation foam from a hardware store and make a little scale one i guess.

a lotta guys hot wire EPS. get a heated up wire, through a battery or something, and then it just cuts right through. get on swaylocks, got some really smart guys on there.

[grub]

...Some of the epoxy boards are still hand shaped. I have looked at a finished product and it does not look much different than a fiber glassed board. I was told that the spider cracks and pressure dents will not happen like a glassed board. But, a board nose caught on a rock or in the sand or hit in the wrong area by a thick lip could still break the board...

Thanks "Dopey", but I am not actual interested in "Epoxy boards"... have a fair understanding of the apparent benifits and weaknesses of epoxy boards when compared too traditionally glassed boards... My interest is in the foam core that epoxy boards use... Hence: EPS
___________________

"its more important to understand than to be understood"

[deathfrog]

you guys got it all wrong

basicly sinista, you were kinda right the first time, it's just another core material.

it's not molded, but cut out of bigger blocks to make blanks, then shaped like a clark blank would be into a surfboard like shape. It's a bunch of little beads of foam, all bonded together with heat. There's also XPS, which is extruded poly styrene, and it usally has delam problems when used in surfboards. Just like clark blanks, you can get eps in different densities, 1-1.5# being used as a core in sandwich construction, 2# being equivelent to a ultralight clark blank, 2.5 being close to superlight, 3 for blue and 4 for green, but unlike polyurethane foam, all of these don't stay permenently crushed, but rebound back and don't pressure dent as easily.

after that, when you glass it, you can't glass it with poly resin because eps foam being explanded poly styrene, and poly resin containing styrene, it'll melt away your foam. So, instead, you glass it with epoxy resin, the same way you would be glassing a clark blank with poly resin.

then, you get a lighter, stronger board, just made out of different stuff.




you can also do lots of cool sandwich stuff with it, and come up with surfburgers and surftechs and stuff.




then there's also boards that line a mold with fiberglass mat soaked with epoxy resin, and blow polyurethane foam into it, creating a popout that's also known as an epoxy board...

[tomcat360]

what'd we get all wrong? oh yea, I was talking about Extruded Polystryene not expanded. not sure if I was clear about it.

[grub]

... you can't glass it with poly resin because eps foam being explanded poly styrene, and poly resin containing styrene, it'll melt away your foam. So, instead, you glass it with epoxy resin, the same way you would be glassing a clark blank with poly resin...

Thanks mate, that was the sort of info I was after... I had an idea that the std. resin wasn't compatable... so really the coating material just needs to be diferent hense epoxy...is there any reason why a stringer cant be added to the blank to increase weight, not primarily use as a stiffiner?

[deathfrog]

no go for it...

but since stringers aren't included, go the better route and use perimiter stringers for a beter flex pattern, or denser foam to add weight

[sinistapenguin]

Right, that's what I thought.

basically you can make the plastic NSP type boards from it, but essentially you can still make a decent quality board if you use the materials in the same way as regular boards.

I made a bodyboard for my sister out of XPS - it is pretty hard to shape, but if you take your time and really go for the quality you can get as good a shape. I had a really nice shape for my body board, then I made the fatal 'normal resin' error and immediately about a 1/4 of the board just melted and I mean quickly!!

I had to completely start again!

I did some more reading after I posted this and it does seem that you can make a pretty decent, strong board using EPS/ Epoxy - it doesn't have to look like a Bic/NSP!!

There was also a site which told you how to extract the Clark Foam core from a board. I can see a few people 'recycling boards' like this.

Basically if you had a big/floaty funboard that was totally wrecked, you could probably get the glass off it and shape the foam inside down to a nice shortboard and reglass it.

Pretty cool considering my mate's got one that he's thinking of dumping cos it's all cracked and damaged.

Cheers

Sinista

[tomcat360]

not to burst your bubble, but on that board look out for spots where water has penetrated the foam, you could probably shape it out and use interior/exterior drywall spackling.

good luck and post pics when you're done!