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Polyurethane for climbing holds

Original Post
S. Fischer · · Unknown Hometown · Joined Feb 2011 · Points: 35

So, I'm building a backyard wall and am trying my hand at making my own holds. After much experimentation, I've got the molding process down and the holds I've cast in Polyester look great.

I'd like to switch over to making them out of polyurethane for a little more flex and a little less brittleness. I'm not really sure where to start in sourcing the polyurethane. After doing some reading, it looks like I want a rigid polyurethane, but there are so many different types. Has anyone played around with this?

Any tips would be great.

Thanks.

EDIT - If this needs to be moved, so be it. I wasn't sure where it belongs.

ErikaE · · Unknown Hometown · Joined Dec 2010 · Points: 5

You might check out Reynolds Advanced Materials (www.reynoldsam.com). They sell urethane plastics for various mold-making and casting applications. Some of them will set in as little as 3 minutes. You shouldn't need any specialized equipment. I'm familiar with the Smooth-Cast 300 series, but any of their rigid urethane plastics should work.

I'd guess they're a bit pricey--you might be able to source something similar for cheaper. If you decide to go with them, Reynolds has filler materials that you can add to the plastic to stretch it out a bit.

rock-fencer · · Columbia, SC · Joined Dec 2009 · Points: 265

aluminite i think the company is called will have some

the stuff is expensive across the board!

S. Fischer · · Unknown Hometown · Joined Feb 2011 · Points: 35

Thanks. I'll start to look into both companies.

Evan Sanders · · Westminster, CO · Joined Dec 2010 · Points: 140
rock_fencer wrote:aluminite i think the company is called will have some the stuff is expensive across the board!
The company name is Alumilite, but yeah they are extremely expensive. I used some of their stuff a while back and it wasn't worth the cost at all.
Andy Librande · · Denver, CO · Joined Nov 2005 · Points: 1,880

Also I believe a fine sand is used in many climbing holds as a filler for resin holds, however I am not sure if polyutherene holds have sand filler in them.

Three Ball Climbing also has a instruction book for purchase, however it doesn't disclose their material sources: threeballclimbing.com/how_t…

Let us know how it goes! I have always been interested in creating some holds and had one failed experiment using resin and haven't tried since then.

Christopher Bastek · · Unknown Hometown · Joined Sep 2008 · Points: 45

Three Ball Climbing also sells all the materials in smaller quantities. You just have to call them to order. 480-334-4646

S. Fischer · · Unknown Hometown · Joined Feb 2011 · Points: 35

Thanks - I've now ordered some small sample sizes from

Reynolds Advanced Materials
Polytek
Aeromarine

I'm trying to stick to 70-75d harness and I don't mind ordering larger quantities since I'm planning to make quite a few holds... just not 55 gallon drum quantities.

So far, I've made a number of polyester and polyester/sand holds. I'm not sold on sand as a filler. The texture is like sandpaper and doesn't really portray the rock I climb. Besides, I have a feeling it will start tearing up my skin. I'd like to start testing the various materials and see what suits me.

Edit - I've ordered some microfillers for the Polyurethane. I'll post up some of my results.

S. Fischer · · Unknown Hometown · Joined Feb 2011 · Points: 35
S. Fischer · · Unknown Hometown · Joined Feb 2011 · Points: 35

I still need to mount em up, but my guess is that they'll be too rough for prolonged pulling.

ErikaE · · Unknown Hometown · Joined Dec 2010 · Points: 5

Did you just make negatives of commercial holds, or did you design them yourself? What are your molds made of? I'm curious--I'm a materials engineer. :)

TheIceManCometh · · Albany, NY · Joined Aug 2011 · Points: 621

I'm planning on building a backyard wall in the spring. Please definitely post your results. Your holds look great!

p.s. also looking at the "how to save money" angle as our wall will be 8 ft wide x 20 ft high (mounted between two tall pine trees).

S. Fischer · · Unknown Hometown · Joined Feb 2011 · Points: 35

My holds are all original. I carved the masters from blocks of "desert foam" used for floral applications.

I read quite a few internet write-ups about molds and found the silicone caulk method to be troublesome. I would spend so much time carving a foam model only to be disappointed by air bubbles and inconsistent curing rates. I was also only getting about 4 or 5 casts before the mold would tear.

I also tried liquid latex, which works well for everything except the bolt hole detail. I had a difficult time getting the latex thick enough in the recess while still allowing it to cure. Plus it took 8-10 coats and lots of time/patience.

So far, I am happiest with a pourable 10:1 silicone that doesn't need to be vacuumed. While it is certainly more expensive, I am justifying it by being able to cast as many holds as I want. One trick is to shape your holds so that when you orient them, they have multiple purposes. This way you can get multiple different scenarios with limited number of molds to make.

There are lots of cheaper ways to make holds if you're doing a limited number and don't want/need to make your molds hold up over time. There's lots of information out there on using single use clay molds as well as packed-sand molds.

For the budget minded, Polyester or concrete is the way to go. I'm not convinced they will last the longest though. I set aside some broken rocks from my last trip to the crag, but sadly I neglected to grab them as I was packing up. I've heard you can carefully drill them and mount them up as well.

Andy Librande · · Denver, CO · Joined Nov 2005 · Points: 1,880

You might want to message MP User Justin Sanford as I have bought holds from him before that he has made and really liked his polyutherene holds.

User profile: mountainproject.com/u/justi…

Kevin Stricker · · Evergreen, CO · Joined Oct 2002 · Points: 1,197

Try sanding down your holds with sandpaper, 120 grit should take some of the bite off.

S. Fischer · · Unknown Hometown · Joined Feb 2011 · Points: 35

I tried some without sand yesterday and they had the same texture. I'm guessing now that the texture is from the foam I used. I may try some new foams or start sanding my foam with a real fine grit before molding.

I'll try sanding down the holds I do have with some fine grit as well. Thanks for the advice.

Mike Lane · · AnCapistan · Joined Jan 2006 · Points: 880

Instead of fine sand, get some granite dust from a tombstone shop. You can take all you want for free usually, they have tons.

Josh Morgan · · East Lyme, Connecticut · Joined Oct 2013 · Points: 0

S. Fischer, What are you using to add color to the resin? Those holds look sick.

rocknice2 · · Montreal, QC · Joined Nov 2006 · Points: 3,847

Texture definitely comes from the mold not the filler.

Jason Hayden · · North Clarendon, VT · Joined Oct 2010 · Points: 9,585

Don't use filler with polyurethane as it will weaken the holds. Your texture will come from the foam and can be adjusted by different sanding methods. Aeromarines resin is pretty good I have some four year old holds in gyms that I made with their resin and they are holdong up well. I'm a fan of semi-rigid as most walls have some variation and a small amount of flex is good to have when you are cranking a hold down.

David F · · Unknown Hometown · Joined Mar 2014 · Points: 0

A Greeting.
I start my journey on the Mountain Project with a question, if I may ?

How the hell do you stop the PU wearing out in ten minutes ? I have had several attempts, using 65 and 70 D resins, and they have the characteristics of hard cheese.

I eagerly await an answer, and thank you in advance.

David.
Boulderer.

Guideline #1: Don't be a jerk.

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