Does Epoxy Dissolve Backcountry Ski Core Material?

Post by blogger | April 14, 2005      
Cutting a backcountry ski in half.
The ultimate coreshot. Cutting a Black Diamond Crossbow ski in half for testing.

At 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.

Backcountry ski epoxy test.
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 backcountry ski.
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.

Ski core foam in epoxy puddle.
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.


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22 Responses to “Does Epoxy Dissolve Backcountry Ski Core Material?”

  1. Ali E February 21st, 2009 4:59 am


    Slightly random post to ask this question, but I noticed there was a picture of a screw next to the bit of core foam in the puddle of epoxy. Is this the TLT Speed screw? I recently bought a pair of TLT Speeds off Ebay for my Scottish rockhopper skis and they came with very similar screws. All are the same size, for heel and toe, with countersunk heads. They seem a lot shorter than the screws for my Comforts, which are different for heel and toe. Will the shorter Speed screws give enough bite?

  2. Lou February 22nd, 2009 2:16 pm

    It’s just a screw to give the photo some scale. In terms of how screws will bite, you just measure how much they protrude from bindng, doesn’t take much if the ski has a strong mounting plate or metal top skin.

  3. Nick February 10th, 2010 2:08 pm

    Hi Lou – I’ve downloaded the templates you have for mounting the Freerides and I’m putting them on Atomic Janaks. I just spoke with a dealer who said to use a water-based wood glue instead of epoxy. What are your thoughts?


  4. Lou February 10th, 2010 2:53 pm

    My thoughts are that epoxy is better. Wood glue costs less, takes less time, and is easier to reverse. Hence, dealers still like it. In any case, if you’re going to use wood glue, use something that’s not water based. Gorilla Glue works well, though it’s not as heat reversible as hardware store epoxy. Why in the world someone would use water based wood glue on something that’s frequently wet is beyond my understanding. Perhaps it’s to introduce controlled obsolescence?

  5. Nick February 10th, 2010 10:45 pm

    Thanks Lou – I don’t live in the states, so I can’t run down to the local hardware store or Home Depot, but there are markets here that sell nearly everything. I have seen epoxy that comes in two tubes of clear liquid … seems to me that this is standard epoxy. Does that sound right to you?

  6. Lou February 10th, 2010 11:00 pm

    Nick, yes.

  7. Peter December 28th, 2010 9:55 am

    As someone who has used epoxies, polyester and vinylester resins with foam,balsa and wood cores over the last thirty years I know that the problem with dissovling a foam core is associated with solvent based resin systems like the polyester and vinylester resins, not epoxy resins. In particular styrene foams dissolve readily with these as the resin solvent base is styrene. Other foam cores can soften if too much solvent is trapped in the foam. This would be unlikely with the small amount of resin used to set a screw. Epoxy resins are not solvent based and do not have this problem. I hope this helps. As a side note any foam core can be damaged by excess heat and I have seen this when thick laminates with lots of resin cure quickly and exotherm a lot of heat in a short time.

  8. aviator December 28th, 2010 10:05 am

    I agree with everything you said.

  9. Greg Louie December 28th, 2010 10:09 am

    Nice concise explantation, Pete. Thanks! I’ve been setting screws in foam core skis for decades and suspected as much.

  10. Thijs Nijveldt April 4th, 2011 8:17 am

    if you use the heating of the screw to get it undone agina, you might consider using “mold release wax”.
    I use this when I want to create thread in epoxy, and need to remove the screws after the epoxy has cured.
    This mold release wax will create a very small layer on the screw to which the epoxy cannot attach. Works perfectly, and this might prevent damaged skis from overheating with the soldering iron!

  11. Michael Brown October 27th, 2012 9:45 am

    Any tips for getting screws out that have been epoxied in?

  12. AVIATOR October 27th, 2012 11:23 am

    like it says in the OP and the comments above
    “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.)”

  13. Lou Dawson October 28th, 2012 2:29 pm

    Thanks Aviator!

    I’ve been up at WildSnow Field HQ for the past couple days. Thanks all the friends who showed up, we got a huge amount of work done. Slash burning complete, water tank shed ready for winter, and the teepee Caleb, Jen, Ty, Kate built is like the perfect summer camp Native American sort of thing — if you overlook the plastic tarp covering it (grin).


  14. Lou Dawson December 3rd, 2012 4:26 pm

    Not sure where to post this… but had an interesting experience today:

    Dynafit Radical series bindings have aluminum toe base instead of steel. Aluminum conducts heat like crazy. I tried to use my old trick of a soldering iron to heat up epoxied screws, and they wouldn’t come out because alu conducted all the heat away! Ended up breaking a torx bit, groan! Solution is probably a hotter heat source on the screw. Whew. Yea have been warned. Lou

  15. See December 3rd, 2012 7:44 pm

    I’ve mounted and unmounted a few bindings with epoxy and I’ve never had a problem just twisting out the screws with a big screwdriver. I’ve mostly used West System epoxies. I usually use just enough glue to bond the threads to the ski. I’ve never had to use heat to remove a screw, nor have I had any screws pull out. Are you guys just slathering on the epoxy or what? I’ve been wondering about this for a long time.

  16. See December 3rd, 2012 8:13 pm

    FWIW I’ve never mounted radicals and, by my measurements, the business end of a T-20 bit is less than half the diameter of a binding screwdriver.

  17. Greg Louie December 3rd, 2012 11:16 pm

    IMO, the Torx 20 connection is a bit wimpy; they should have gone with a T-25 or T-30. I’ve been replacing some of them with normal Pozidrive screws.

  18. Lou Dawson December 4th, 2012 6:16 am

    See, we’re just being careful. Indeed, many epoxied screws can be removed without heating. One thing nice about heating in addition to no chance of ruining screw driver or screw is the threads come out cleaner.

    I’d agree that the T-20 is a bit weak. Totally fine for insertion of the screws, but could be stronger during removal. I got some impact-driver rated bits that are probably stronger.

  19. Rob August 26th, 2014 9:04 am

    Wow, that bumped up an old story.

    But Lou, it reminds me of a question that I have been meaning to ask you. Do you know what the impact of heating up cured epoxy is on its strength once it cools back down? The dilemma I have is that a few years ago was forced to use gorilla glue to secure some fasteners into inserts (quiver killers). I would like to heat up the fasteners to remove them (and the bindings). The quiver killers are epoxied into the ski. I am concerned that the heating of the fasteners will impact the hold of the epoxy on the quiver killers. Thoughts?

  20. Toby August 26th, 2014 3:02 pm

    Rob, heating up cured epoxy will permanently remove bonding properties of it.

  21. Lou Dawson 2 August 26th, 2014 4:23 pm

    Thanks Toby, I’d add that different types of epoxy are more or less temperature sensitive, but i’d suspect if you heat up those Quiver Killers they’ll come out or at least be weak. Lou

  22. Skihelm September 22nd, 2014 1:29 am

    Nice article, thank you for the explanation!

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