epoxy or polyurethane for repairing broken limestone holds?

Original Post
Ryan Arnold · · Unknown Hometown · Joined Jun 2012 · Points: 315

I bought these two glues to repair the jug on Princess Di.  What will work better for limestone, epoxy or polyruethane?  Any tips for effective glueing?

20 kN · · Hawaii · Joined Feb 2009 · Points: 1,128

I dont know what the ethics are in American Fork, but I dont really know of many areas that are cool with gluing holds back on that broke off previously, especially ones this large. Some areas allow selective reinforcing of existing holds, but even that is limited. I'd ask the opinion of other people before doing anything--specifically the FA and other people who climb there very often. You should develop a strong consensus before taking this type of action on a route as popular as the one in question.

Anyway, glueing a hold back on that large wont work, and it rarely works even with small holds. If you absolutely must reattach it and locals are okay with it, a better option would be to drill through the center of it, line it back up into place, and then run the bit through the hole on the hold and into the main cliff rock. After, epoxy a piece of threaded rod entirely within the hold and into the rock, and optionally reinforce by adding epoxy around the cracks. Seal the threaded rod hole closed and find a way to wedge the hold into place for 24hr. If the threaded rod is not inserted perpendicular to gravity, you'll have to find a way to wedge the hold, threaded rod and epoxy into place. This is a technique used to bolt on large flakes which cannot be trundled or epoxy reinforced. It allows one to structurally reinforce an existing dislodged feature with minimal visual impact since the entire rod is inserted into the rock and the only thing visible is a 1/2" hole filled with epoxy. Using this technique, drill the hole to the same size as the threaded rod diameter. For a hold, you’d be fine with a 3/8” hole and 3/8” threaded rod. Instead of threaded rod, you can also use an adequately long wedge bolt. To do this you would need to countersink a hole large enough to fit the nut, then once you bolt the piece back on you then seal the nut into the hole with epoxy and level it out flush. This option is much, much easier as you dont have to wedge anything in place for 24hrs, but it requires a larger SDS bit for the countersink.

Dont use the stuff in your photos. Use a two part epoxy mixed through a nozzle such as these:



You can find both products at Home Depot. The top item cures dark green and I think the bottom one is red. You can help camouflage the epoxy by painting it after or by sprinkling dirt on from the ground which is the same color. Ultimately neither are permanent solutions and after a few years the color of the epoxy will come to the surface, which is in part why you want to be careful as no matter what you do it's going to become visible.

Guideline #1: Don't be a jerk.

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