Sterling hollow block slings losing "grippiness"

This past season I've been using Sterling hollow block slings for backing up rappels (autoblock attached to a biner attached to leg loop). Initially they worked great - 3 wraps generated sufficient friction to arrest the rappel when going hands free. However, these slings have picked up a considerable amount of dirt and have also frayed a little bit on the surface. Lately, about half the time I set up the autoblock, 3 wraps is not sufficient to brake the rappel. I find that I have to be very careful about dressing the autoblock in order for it to grip the rope sufficiently. Has anyone else experienced this? Going to 4 wraps produces way too much friction. I'm considering going back to the normal prusik cord for backing up rappels.

Consider using a friction hitch with a single strand vs. a tied loop. It will give you more flexibility/adjustment for fine tuning the friction needed.

Using a loop, every time you wrap the rope, the loop makes two, four, six bends. If you use a single strand, you could wrap it and get 2,3,4,5,6 bends depending on how many times you wrap the rope.

A length of 6 mm cord with "8's on a bight" on both ends will allow you to use the conventional autoblock hitch as well as some other esoteric friction hitches.

Same rope each time? I've been using a hollowblock all season with no perceptible change in friction. It's never fully locked up with 3 wraps on a super skinny 9mm single with dry treatment, on those ropes it would creep ever so slowly when new. Older and fuzzy super skinny ropes it does lock up fully.

You could also change your hitch. Try a Kleimheist with three wraps instead of an auto block.

Nick Drake wrote:Same rope each time? I've been using a hollowblock all season with no perceptible change in friction. It's never fully locked up with 3 wraps on a super skinny 9mm single with dry treatment, on those ropes it would creep ever so slowly when new. Older and fuzzy super skinny ropes it does lock up fully.

Stop backing up your rappel.

Ray Pinpillage wrote:Stop backing up your rappel.

I've used the same hollow block for over a year for every rap I've done in that time frame and I haven't noticed any chance. Maybe wash it?

Wrap it 3 times then twist the end bight a time or two before clipping it back in to the locker.

slevin wrote:Wrap it 3 times then twist the end bight a time or two before clipping it back in to the locker.

slevin wrote:Wrap it 3 times then twist the end bight a time or two before clipping it back in to the locker.