Testing new materials before using them

[Head Monkey]

I want to pass along a friendly tip to everyone that may not necessarily be obvious. This subject has come up when talking to a bunch of people in the just past few months. Whenever you get a new material, you should perform a bonding test with the rest of your system before using that material in a real layup. Everyone is using rather different processes in terms of material preparation, epoxy system, layup, heat, pressure, etc. What works very well for one person may actually not work well at all for another when many of these variables are changed. And sometimes manufactures actually send out bad material, or even epoxy.

Whenever you get new epoxy, you should label the cans, always use them in sets, and mix a 100g test sample, cure it properly, and do a basic stress test on it (i.e., break it). Ensure it behaves as you expect, and as it has for you in the past. One time I got a can of resin that was incorrect, and the 100g sample made the problem obvious. I took the cans and the sample back to the manufacturer, and they apologized and replace it right away.

The same goes for most of the materials that go into the board: glass, base, VDS, top sheet, sidewalls, any extra special reinforcements you might be using. Test each one with your epoxy, pressed and cured properly, and see how it bonds to the adjacent layers. The only materials I don’t do that with are the wood cores (poplar is pretty much poplar no matter where or when you get it), and the edges (unless I’m switching from plain steel to edges that may have a rust inhibitor.)

There’s a lot of material out there that technically has a shelf life: flame treated base material is a fine example. In theory, the treatment degrades over time, yielding a weaker bond. If you have a large stock of such material that you are working through slowly, then consider re-testing a sample periodically.

Finally, if you change a preparation technique, again do a sample layup and test it before using it in a real layup.

If you’re selling your boards or skis, I highly recommend recording which batches of material and epoxy you use in each build. Save the tests so you can refer back to them if someone reports a problem.

I hope that helps.

[OAC]

Good subject there! Should be in the howto, if it's not already there.
I've been too eager sometimes, but realize that taken it easy saves me money!

[knightsofnii]

the testing of epoxy batches is a splendid idea, i think we will incorporate that