Which epoxy?

[windsurfer]

I would like to build my second pair. I'm looking for the right epoxy.
I found a german website that sells 3 different epoxies:

-Standard
-Industry
-and for the aircraft industry

The characteristics of the epoxies differ:
tensile strength: 55 to 80 N/mm²
expansion: 3 to 6.5%
bending strength: 80 to 120 N/mm²

Does it really matter, which Quality I buy? Who has experience with different types of epoxy?

Thanks a lot!
Karsten

[knightsofnii]

there are hundreds of different kinds of epoxy.

try to find a company making epoxy FOR SKIS or Snowboards.

aside from that, I'm not sure what's over in Europe regarding good ski/board epoxies.

Marine epoxy (ie west system) is a diluted version of the better epoxies designed for compression molding. Apparently marine epoxy is designed to bond wood to wood often, so its low viscosity and absorbs into your core more.


try to contact Roy from QCM, ask him if he's got a recommendation for you for something in europe. He seems to care more about people getting the right stuff, than about making sales.

[windsurfer]

Thanks a lot for your answer! Do you have specifications regarding the viscosity, elasticity, etc. for your marine epoxy?

[windsurfer]

another question:

Is a viscosity of 600 mPa*s low for epoxy?

Its supposed to be a low viscosity-epoxy, there is also a medium-viscosity-epoxy with 5000 mPa*s

[davide]

You can buy the R&G type L with hardener L (40 min.). It is easy to use and great for skis.
http://shop.ezentrum.de/4DCGI/ezshop?hid=27&sprachnr=1

[knightsofnii]

i was trying to say DO NOT buy/use marine epoxy.

it works ok, but you can do WAY better with something more specific to skis/boards.

medium viscosity is probably better, usually produces a stronger board.

I use a medium/high viscosity resin, with a low viscosity hardner, when combined it's a medium viscosity, slightly thicker than marine stuff.

[H-man]

Pretty much any "standard" epoxy will do but the characteristics can be helpful if understood. Heat curing is a big issue for those not willing to spend money on heat blankets and controllers so researching which epoxies cure at which temperatures may save you a headache. Post curing is also a factor in choosing a resin system depending on your capacity to post cure at temperature or not. Contact your supplier and discuss what you can and cannot do in order to get an appropriate resin for you.

[hafte]

O.T. alert

Windsurfer, I apologize for the thread drift, but I had to ask.

knightsofnii, can you back up any of your assertions about marine epoxies? I don't want to hear what you think. I would like to see some research, engineering, test data etc. Anything that you can provide to back up your statements would be appreciated. I’m willing to learn. Please enlighten.

Thanks

Hafte

[H-man]

some typical datasheet/property pages for typical epoxies:

http://westsystem.com/ss/typical-physical-properties/

http://www.resinresearch.net/id8.html http://www.resinresearch.net/id9.html

http://www.resoltech.com/IMG/pdf/DS-1020T-06-07.pdf

http://hp-textiles.com/proddat/Hochlast ... 111L_E.pdf

just a caveat, I am sure Doug knows what he's on about with the resin thing but I am also confident he will agree with me that most standard resin systems will be sufficient for the average home build boards/skis. When you want to get all high performance, then I would be inclined to say that researching the resin a bit further will be needed.

I have built some vacuum bagged boards with resin research and with HP textiles resin. The latter having a slightly better result but was that due to the resin or due to my curing temperatures...

When building composties it is often the details that get overlooked, like making sure your fiberglass is clean and dust free, ensuring there is no oily or waxy stuff in the board/ski materials (after rubbing in your steel plate with mould release agent...) and of course curing and post curing issues...

[Alex13]

Hi hafte,

On the epoxy hard data, I doubt there's a lot out there. Ski & Snowboard making is still more of an art than a science, and is heavily based on trial and error - even with the big boys like Burton and K2.

Generally though, ski/board epoxies are developed with specific properties in mind compared to marine epoxies. Skis go down to very low temps, -25C or lower, and need to maintain flex at those temps. Skis also need to be flexible, boats are generally much more rigid. Marine epoxy is more likely to fatigue earlier than ski/board epoxies developed with repeated flex in mind.

This is not to say you can't make a ski or board with marine epoxy - of course you can, but you're likely to get better results using epoxies that are developed for the purpose.

[hafte]

Windsurfer, the products I use have three modulus of stiffness. They can be mixed and matched to suit my needs, but that takes time and testing. Without test equipment and procedures it would not be possible to quantify, and as you can see anything we say would be speculation, anecdotal, and opinion.

At a 3:1 mix I could buy a 4 gallon kit and do some testing to see what would work best for me, but again would be very subjective and difficult to quantify any meaningful way. Instead I looked at my processes for construction, how much I had to spend (heated vs non heated press etc.). Then I made a choice on the type of epoxy that would work best for my situation. In the end I went with the mid range modulus epoxy from my supplier. Reasoning the too stiff would break/ shear apart easier under the stresses of skiing and too soft... well just wouldn't be as satisfying. Oh wait, would be too much of a noodle and wouldn't ski as well in difficult snow conditions.

Any way you go I think you'll have fun with the results. Enjoy your project.

Hafte

[knightsofnii]

if you're in Europe try to look for the company that makes the epoxy for Huntsman, not sure if its called Huntsman or Ciba or Ciba-Geigy, but they're now owned by Huntsman. There are a couple others over there that the community likes as well. But yea, i mean you're not going to end up with a BAD board with west system, but it is a little more fragile.

A good affordable off the shelf epoxy that we started off with was the Mr. Fiberglass epoxy. Somewhere on the web there's a page where someone found out the company that makes the stuff and the part numbers, etc, so its still available. Mr. Fiberglass just rebottled it and sold it with their brand. I say this because Mr. Fiberglass is gone . Compared to the QCM epoxy I use, it seems a little stronger actually, but less lively flex wise, a little heavier. Though those were our first couple boards, I should build a new board with it and see what happens.

[sammer]

I've been using west system for the last 7 pair of skis.
It's been working fine. I usually post cure heat to about 120f for 6 or so hours with an old electric blanket.
I've got 56 days of abuse on the first pair of everydayfatties and they are still holding up, no signs of delam.
Might be a little mushier than when new but still a ton of fun to ride.

sam