Milking & rope balance

Does anyone here make it a habit to throw a prusik on new double-braid line and milk the entire thing before using it for the first time?

My understanding is that all double-braid rope should come from the factory with the sheath and core approximately balanced, and that this balance allows the cordage to reach full tensile strength and share the load effectively.

So, when splicing, one should be careful to not disrupt the balance more than necessary - which is why the rope is knotted/pinned ~ 5 feet back from where the splice occurs.

When this balance is off (eg, the rope has a reputation for milking, the factory was having a bad day, it got mishandled at a distributor, etc), the advice I came across most often here is to just climb on the rope with the core unattached at the tail, and allow it to balance itself out naturally, then remove the excess sheath.

"You should always milk a double braid rope when you first purchase it, and we will show you how to do just that. " -SherrillTree

I made this "mistake" once with an 80' length of Velocity - milked dozens of inches of sheath off before the whole situation smelled bad and I did some more reading. (I was able to get the sheath back on, and after a dozen or so climbs, the sheath hasn't milked more than an inch or two.)

That's a good thread - anything with Brian Toss and Nick is gonna be good.

I made a few calls yesterday - Samson says to contact SherillTree or Wesspur with any technical questions on arborist cordage.

The rep at Wesspur said that a blanket recommendation to pull the sheath tight on climbing lines wasn't something he'd heard of, "seems surprising that the factory would spend a lot of time and effort constructing the rope, then to send it out and have step one be to mess with it."

New England/Teufelberger: Said that it shouldn't harm anything, but isn't something they normally recommend for their ropes, but that it may be something that users of "lower quality ropes" want to do to to prevent milking from being a problem in use. He made it a point to say several times that it won't hurt anything, and to also contrast with other "low quality ropes." (They must be very proud of that Tachyon jacket. ;))


Well-Known Member
If you could harm the rope in any way doing that, what do you think would happen the first time you descended on it with a prusik? You can't walk backwards with the rope horizontal and generate anywhere near the forces applied when you load it up with your own weight when it's vertical. I do it all the time with ropes with a baggy feel to the sheath... like the Yale 11.7mm ones. I still descend on it a couple of times before putting it into service, but pre-milking them means one or two descents and it's ready to go, as opposed to five or six descents to get the worst of the milking over with. They usually don't milk more than an inch or two after that.

Either way you do it, it all comes out the same in the wash.
Adam from Yale was kind enough to get back to me with a comprehensive response:

The first and most straightforward answer is NO, it is not necessary to manipulate the core/sleeve balance of one of our products if it has been correctly spliced in accordance with Yale’s splice instructions. All of our double braid climbing products are effectively “milked” before they ever make it to the customer.​

That being said there are a few things to note with respect to core/sleeve balance. We sometimes hear complaints about sleeve milking over time but this is a somewhat unavoidable side effect of the differences in construction and fiber types used in the cores and sleeves of our climbing lines. Our aim is to minimize the amount of milking to the extent that it will not impact most climbers in most situations. The vast majority of people climbing on our products will not encounter issues with milking unless they are climbing on extremely long lengths of rope. If an issue is encountered it will almost always occur after the rope is thoroughly broken in. In this instance our recommendation is to simply milk any excess sleeve slack off the non-spliced end of the rope and cut it back until the core is visible. Typically we’re talking about removing very short lengths of several inches or so. Most people are not bothered by this and I’ve even heard some people find this short section of rope with no core to be useful in pulling the rope through their friction savers as the diameter is reduced slightly. However our recommendation remains to remove the excess sleeve from a climbing line.​

The other scenario we have heard of relate to incorrectly performed splices. For some of our products (XTC-24 in particular) it is necessary to actually add a small about of sleeve slack in order to accommodate the splice. When performed correctly the amount of slack added will be entirely consumed by the splice process and there will be no net-addition of sleeve slack to the rest of the rope. However if the rope is incorrectly spliced some slack might remain. Unlike the previous scenario this will be most apparent on short lengths of new spliced products. The worst case scenario is a short eye-eye lanyard or something similar where the slack cannot be removed from the rope by milking it off the end. While it may be appealing to milk the excess slack off the end of the new rope, I would caution you to not “over-milk” the rope. If you are inclined to remove sleeve slack from a product I would be careful to check the splice has been performed correctly and that milking is performed by hand and not with the assistance of a machine or other rope-grab device.​