Does Epoxy Dissolve Backcountry Ski Core Material?

The ultimate coreshot. Cutting a Black Diamond Crossbow ski in half for testing.

At WildSnow.com HQ, a Black Diamond ski box was parked on the porch, full of skis that would have otherwise ended up in the dumpster at BD.

What am I doing getting BD’s dregs? Read on.

For years, we’ve used epoxy for the screws when mounting ski bindings — telemark and AT randonnee. Doing so yields a trouble free mount that never loosens, has better pull-out strength, and is totally sealed against moisture.

And, for years people have told us we could not or should not use epoxy for mounting bindings.

“You can’t get the screws out,” they said, “and epoxy will eat away the core foam of some skis, especially Black Diamond models.”

Well, we got tired of all the nagging.

Our experience is that hardware store 5-minute and 1-hour epoxy worked fine with ANY ski we’ve ever mounted, and if you count the ones I worked on back during the 1970s days of Company 3 and their distribution of the Ramer binding, and dozens since than, that means HUNDREDS of skis — everything from wood x-c skis to metal sandwich construction, to honeycomb core, to modern AT skis, and on and on.

But how do we know for sure about this? After all, it’s tough to see inside a ski and check what the epoxy did in there.

Solution: Black Diamond was kind enough to send us a few pair of late model skis they had destined for the dumpster — for what I described as “experiments,” with a mad scientist slant.

Filling the screw hole with epoxy.

1. We sectioned a ski to look at the core, and test our cutting method (abrasive wheel with water spray). The cut was clean, and exposed un-damaged core material.

2. We drilled a mounting hole, filled it with epoxy, then inserted a screw. After giving the 5-minute epoxy an hour to cure, we heated the screw with a soldering iron and removed it, then carefully sectioned the ski exactly at the edge of the screw hole, so we could see the hole from the side. Result: a nice threaded hole with hardened epoxy, no core damage or dissolving foam whatsoever.

Cutaway at exact edge of epoxied screw hole. Epoxy cured nice and hard, with no damage to foam. What you’re actually looking at here is a thin layer of epoxy on the near edge of the screw hole, somehow our cut was accurate enough to leave that intact. Didn’t know we could use an el-cheapo cutof saw as a micrometer — but it happened!

3. We cut out a chunk of core foam, placed it in a puddle of epoxy, and let it cure. Result: no damage, no dissolving foam.

We placed this chunk of Black Diamond core foam in puddle of epoxy, then let it cure. It remained rock solid. We’ll keep these and observe over the next few weeks to make sure there is not long-term problem with the foam/epoxy combo. We’ll also do this same test with different brands and types of epoxy, and report back here.

4. Lastly, we repeated the “puddle” routine with foam from the other skis BD sent us, in case there was a difference.

Conclusion: We will continue to mount skis using 5-minute epoxy for the screws. To remove, we simply heat each screw for about 30 seconds with an electric soldering iron (experiment, you may need more or less heating time depending on your soldering iron, size of screw, etc.)

Caveat: Our test does nothing to prove there is not SOME ski out there that doesn’t like epoxy, but judging from this and past experience, I’d say that unless a ski maker specifically says to NOT use epoxy for mounting , it’s a safe way to make those binding screws bombproof! (We’ll see what BD says after they see this, as it’s said they recommend against using epoxy for mounting.) Also, bear in mind there are numerous flavors of epoxy. We’ll try our “puddle” test with a few more brands, and report back if we find any that do damage the foam.

Update: As of 2007 Black Diamond skis have wood cores so this issue is moot for that brand, but many other brands of skis use foam, and my guess is that epoxy is not a problem with most, if not all.