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Potential solution for repairing cam thumb loop coating


Original Post
Scott Scharfenberg · · Santa Barbara, CA · Joined Jul 2013 · Points: 15

I recently discovered that the coating on the thumb loops of nearly all of my Master Cams has blown through to the cable.  My CCH Alien offsets are also nearly blown through.  Yikes!  This is a result of my partner and I clipping aiders and fifi's to the thumb loops repeatedly on big walls.  I'm glad that I caught it before anyone got hurt or my slings got shredded.

Naturally I launched into research on how to best fix this issue.  I found almost nothing with all my Google-fu, so I contacted Metolius.  They told me to use electrical tape.  I'm sure several layers would be adequate to protect the sling from the cable in the event of a fall while free-climbing, but there's no way this solution would stand the test of a big wall.

I knew I wanted something like Plasti-Dip tool dip, except much stronger.  After a lot of research I eventually settled on Urecoat, a two-part flexible urethane coating made by Smooth-On.  It has a Shore A hardness of 70, which seems to be right at the intersection of flexibility and strength that I'm looking for.  Unfortunately this stuff is not cheap.  I decided to take a gamble and buy the gallon kit, since I knew the trial size would not be enough to fix my rack.  It was far more economical to go big rather than buying multiple trial sizes.  Hopefully my friends will be grateful when their thumb loops blow :-]  In any case, the gallon kit plus some colors still cost less than two shiny new cams, and apparently Metolius doesn't believe in thumb loops anymore anyway.

So far I've tested this coating on some wire and the results are promising.  I believe I'm one or two more tests away from actually trying it on a cam.  I will follow up here with my results as the experiment continues.  So far it appears I will need to do multiple thin coats to get a result that isn't ridiculously lumpy.  This means a lot of waste, as the stuff pots up in 8 minutes and cannot be reused, but I expected this would be the case.  I think anyone who doesn't care about lumpiness or coloring the urethane before coating their thumb loop would be able to get away with a lot less than I'll be using.

I do not believe either of the individual components, the colorants, or the cured urethane will cause any problems with the sling.  But oh my god this stuff gets EVERYWHERE.  Thoroughly masking the entire cam + sling, so that only the thumb loop is exposed, will be very important.  Don't want urethane in the trigger mechanism.

I imagine there will be plenty of people freaking out and/or trolling, because I'm modifying my gear.  For sure, I'm gunna die.  

If you know more than I do about these materials and have a valid scientific reason why this process might compromise my slings or cause other failure(s) in the cam, please contribute.  I will ignore alarmist conjecture.

If anyone in the Santa Barbara area would like to come help me with this experiment (and get your thumb loops coated), feel free to contact me.

Happy climbing, friends!

Scott

Carla R · · San Jose, CA · Joined Mar 2016 · Points: 110

I have nothing really to add here but just curious if you've also mentioned this plan to Metolius? I wonder what their experience is..they didn't offer up any other fixes or to send them in? 

Sounds interesting. Good luck!

Scott Scharfenberg · · Santa Barbara, CA · Joined Jul 2013 · Points: 15

Thanks!  I asked Metolius if they knew of any other solutions like epoxy or Plasti-Dip.  They said epoxy doesn't work (too brittle--it cracks) and they hadn't tried Plasti-Dip.  No offer to do repairs, but I didn't ask.  

I thanked them for the info and told them that I might explore other options, and that I'd let them know if I find something good.  If I'm able to repair my rack I'll definitely share the results.  Would be awesome if they could expand repair services beyond re-slinging and triggers!  

And of course I think that DIY'ers and other cam manufacturers should have access to this info too, provided that it actually works...

Kevin Mokracek · · Burbank · Joined Apr 2012 · Points: 200

Sugru, I have used it in my cams and works ok

Scott Scharfenberg · · Santa Barbara, CA · Joined Jul 2013 · Points: 15

Oh cool!  I'd considered that, but was worried about the durability.  Some Amazon reviews had me thinking it was pretty light-duty.  Do you clip stuff directly to the thumb loops and weight it often?

Kevin Mokracek · · Burbank · Joined Apr 2012 · Points: 200
Scott Scharfenberg wrote:

Oh cool!  I'd considered that, but was worried about the durability.  Some Amazon reviews had me thinking it was pretty light-duty.  Do you clip stuff directly to the thumb loops and weight it often?

I've used it to repair cracks in the loops on my Totem cams and so far it's holding good.   

Idaho Ian · · Pocatello, ID · Joined Jan 2014 · Points: 5

I had proposed using Plasti-Dip products a while ago for coating wire loops on stoppers. I seem to remember people being concerned with water being detained in the wire and causing erosion. Plasti-Dip and similar products are different from the plastic tube-style coverings on most commercial products in that it coats within the wire and might not allow enough air flow for moisture to easily evaporate. That said, I did try it on an old wire I found and it doesn't seem to have problems yet, but I climb almost entirely in dry, desert climate where moisture isn't a problem.

I am not sure if these worries are really founded on any significant evidence. It seems like it would be fine as long as some small section of wire was still exposed

Scott Scharfenberg · · Santa Barbara, CA · Joined Jul 2013 · Points: 15
Idaho-Ian Lauer wrote:

I had proposed using Plasti-Dip products a while ago for coating wire loops on stoppers. I seem to remember people being concerned with water being detained in the wire and causing erosion. Plasti-Dip and similar products are different from the plastic tube-style coverings on most commercial products in that it coats within the wire and might not allow enough air flow for moisture to easily evaporate. That said, I did try it on an old wire I found and it doesn't seem to have problems yet, but I climb almost entirely in dry, desert climate where moisture isn't a problem.

I am not sure if these worries are really founded on any significant evidence. It seems like it would be fine as long as some small section of wire was still exposed

That's an interesting thought.  My plan is to cut the old plastic off and do a single, semi-loose wrap of electrical tape before coating.  This is so that I can have a smoother surface for coating, and easy removal for replacement in the event the Urecoat fails.  This should cover the potential problem of moisture trapping, as there will be gaps between the cable and the electrical tape.   

I think it will also help prevent the cable from internally abrading/tearing the Urecoat.  Initial testing indicates that tears in this stuff make it much more susceptible to further damage in that area.

I did try it on an old wire I found and it doesn't seem to have problems yet...

Have you weighted the wire that you plasti-dipped?  If so, how did it hold up?  This might be a cheaper/more accessible option for many climbers if it works well.

On the subject of cheaper, I've figured out how to be significantly more efficient with the Urecoat.  Rather than making a big batch to dip an object in, it's perfectly fine to make a small batch and just slather it on.  The Urecoat will still be flowing for at least 15mins, so by waving the object around and tweaking the coating here or there, you can get a very smooth coat with much less product invested.  I now believe that a trial size could coat several racks.  I've got enough to open a freaking nation-wide repair shop with my gallon.

Idaho Ian · · Pocatello, ID · Joined Jan 2014 · Points: 5
Scott Scharfenberg wrote:

Have you weighted the wire that you plasti-dipped?  If so, how did it hold up?  This might be a cheaper/more accessible option for many climbers if it works well.

Yes, I actively climb with it. I really wouldn't put much consideration for or against it though, because like I said it was found (in reasonable condition) but also has never been used where moisture might be a problem (at local crags in the desert). It might be a bigger problem if the pieces were used in wet or alpine climates.

 Maybe I will test it with some exposure to moisture then take the plasti-dip off in a couple days to see how much was retained.  

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,530

All of my old stoppers were plasti-dipped. Whipped on alot of them, it never cracked- too soft for that. I cant remember how many dips I did- more than one for sure. Probably two. 

I never considered moisture build-up- i probably ought to cut the stuff off one of these days and check. The only reason i never did on my current set is they already have a plastic coating. 

Scott Scharfenberg · · Santa Barbara, CA · Joined Jul 2013 · Points: 15

Awesome!  So Plasti-Dip seems like a good solution.  Way cheaper than my idea too, unless you're anal like me and want to have all the right colors for each cam, or have more than a handful of pieces to coat.  I kinda doubt the whole moisture retention thing is that big of a deal, but I'm sure a loose under-wrap of something before dipping would result in gaps similar to the original tubing.

I'll continue with my experiment because I've already invested this much in it, but I know what I'll fall back on if it fails.

Thanks for the input!

Scott Scharfenberg · · Santa Barbara, CA · Joined Jul 2013 · Points: 15

After a few experiments with coating insulated wire, I'm pretty confident that this stuff is gonna be TOUGH.  It's really abrasion-resistant, and my original worries about small cuts/tears becoming weak spots for blowouts seem to be unnecessary--I was impatient in my initial tests and had started destructive testing before the full 16-hour cure time was up.  It takes a sharp knife to cut this stuff and tearing it takes a LOT of effort.

Two coats seems to be the right amount, and I learned that you do not want to touch this stuff with bare hands between coats.  Oil from your hands can prevent the second coat from adhering to the first, allowing for the layers to delaminate under stress.  Delaminated layers are more susceptible to tearing.

Going to coat a cam or two tonight and will try to get some real testing in this weekend!

Matt Stroebel · · Philadelphia, PA · Joined Apr 2011 · Points: 115

This sounds pretty similar to aqua seal, which is a one part urethane coating. I've used it to repair a lot of sailing/kiting gear, if what you're trying doesn't work I'd give it a shot, it's really durable.

http://www.nrs.com/product/2291/aquaseal-urethane-repair-adhesive

Guideline #1: Don't be a jerk.

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