What Goes Into the DryXP UIAA Water Repellent Treatment

Chuck Weber, Process Manager Nov 16th 2017
DryXP UIAA Water Repellent Treatment on rope

I hope you can appreciate that we are not at liberty to disclose too much technical detail given the heavy R&D investment we’ve made and the proprietary nature of the entire process. I suspect you’d get a similar response from our European competitors who also worked hard to offer ropes that pass the incredibly difficult UIAA Water Absorption (aka “dry”) test. Modern rope making is a competitive business that has evolved to far more than just simply buying, twisting and braiding yarns into ropes. That being said, we’re glad to go into some general details here.

Sterling has always had top notch quality control and products, but it’s fair to say the precise chemistry and new process controls needed to achieve the UIAA Dry certification required us “upping our game” a notch. Appreciable investment was required in the advanced mixing, dipping, drying equipment and curing ovens now in place at Sterling to ensure we’re delivering top-notch product. Rest assured, no shortcuts were taken!

Let's start at the core

Since the early days, Sterling has always and continues to apply a proprietary coating, our DryCore™, to ALL Sterling dynamic rope cores in the early processing stages. It has evolved a bit over time, but we never changed the name. The benefits of this dual-chemistry component are twofold – one component helps the cores resist water absorption and the other provides increased fiber-on-fiber lubricity well above any competitor’s dynamic rope that does not have cores treated in a similar way. This is one component that helps achieve a longer service life of your rope before the cores turn to mush or the sheath slippage becomes excessive. If you were to cut open any new Sterling rope and apply water drops to the core, you’ll see they are repelled for a short time – where untreated yarns absorb the water immediately. That’s the DryCore in action. On any given humid day, your climbing rope is absorbing a small amount of water out of the air and water is never good for nylon when you’re climbing – strength decreases, friction and stretch increase. Nylon ropes that are untreated are akin to sponges, quickly absorbing water.

On the flip side, you and your rope will appreciate having the extra lubricity added into the cores during those bone-dry days climbing in the desert. Sterling’s DryCore™ alone won’t pass the harsh UIAA “Dry” test, because the sheath has to be treated as well in order to pass that, but we add it to all cores of all dynamic ropes because we believe the cost and effort results in an overall better performing rope.

Moving to Sheath

When it comes to trying to waterproof colored nylons, certainly not all yarns are the same. Even with the correct waterproofing chemical and curing process in place, various colorings and coatings can prevent a yarn from becoming waterproof. So there’s a chemistry balancing act going on to be sure the right yarns are treated with the right percentage of waterproofing chemical and lastly you have to cure (aka “carefully cook”) the rope just right to ensure a permanent bond of the nano-particles to the rope. When we have all this right, we deliver the Sterling DryXP ropes that are certified as UIAA Dry.

  • This is a close up view of the Velocity Bicolor DryXP. You can see that water beads up on the sheath.

Unlike typical dry treatments of the past, the DryXP is permanent. Even typical wear and washing of the rope will not remove this dry treatment. The pre-test abrasion cycles that are required in the stringent UIAA Water Absorption test are meant to “simulate use” and very much help prove to the customer that the dry treatment of the rope being purchased has a far superior permanency than any dry treatment that does not carry the UIAA Dry label.

  • This is an in-house experiment done by our Climb Market Sales Manager, Matt Andrews. This picture was taken 12 hours after the ropes were placed in the water- the one on the left has the DryXP Treatment on the sheath and core, and the one on the right only has DryCore. As you can see, the water has absorbed through the sheath and core and has gotten the paper wet on the non-dry treated rope on the right side. The left side still shows a completely dry rope and paper, demonstrating the effectiveness of the DryXP Treatment.

This test demonstrates how the stringent UIAA Standard administers water to the abraded rope.