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Is anodising slipperier than bare alloy

ironcheff

3-Dec-2012
9:46:24 AM

Teeth are tougher than chalk but is anodising slipperier than bare alloy.

I’m wondering if a brand new tube belay device like an ATC, complete with its glossy new anodised finish has less friction than the same device after it’s had enough use to the point where the anodised finish has worn off the surfaces that make contact with the rope.

Give us your gut feel though if you know of measured test results that would be better.

shortman

3-Dec-2012
10:27:37 AM

I reckon a new belay device is actually grippier.

kieranl

3-Dec-2012
10:42:21 AM

On 3/12/2012 shortman wrote:
>I reckon a new belay device is actually grippier.
I don't change belay devices regularly enough (maybe every 15 years or so) to tell but I would agree with Shortman. The wear from the rope over time would be polishing the device which should tend to reduce the friction.

MarcusfromHamilton

3-Dec-2012
10:53:02 AM

This is only going off my low level education, but wouldn't the "shinnyness" determine the smoothness? And the worn bits on mine seem pretty polished. Just a thought.

One Day Hero

3-Dec-2012
10:56:13 AM

On 3/12/2012 ironcheff wrote:
>
>Give us your gut feel though......

My gut feeling is that someone expending mental energy trying to figure out whether a belay device is slipperier for the first half a day while it still has anodising on doesn't have a girlfriend and hasn't had a root in a very long time!

ajfclark

3-Dec-2012
1:14:04 PM

Totem recalled their early production runs because the contact surface of the lobes were anodised: http://www.totemcams.com/blog/archives/738

Doesn't take much to wear the anodising off a belay device or biner though.

egosan

3-Dec-2012
2:51:30 PM

Mostly friction doesn't matter on belay devices. The force it takes to bend the rope through the device is the larger braking force. Down at the bottom of this very interesting document from Jim Titt it is all explained.

http://www.bolt-products.com/Glue-inBoltDesign.htm

shortman

3-Dec-2012
3:00:20 PM

Mostly??

egosan

3-Dec-2012
4:37:40 PM

On 3/12/2012 shortman wrote:
>Mostly??

most·ly/ˈmōstlē/
Adverb:
1. As regards the greater part or number.
2. Usually.

TonyB

3-Dec-2012
6:21:02 PM

On 3/12/2012 egosan wrote:
>http://www.bolt-products.com/Glue-inBoltDesign.htm

"With only one exception no device available on the market is proven to be capable of stopping a climber in a reasonably long factor 2 fall and with most devices the belayer risks severe rope burns and loss of control even in considerably lower (less than 1) factor falls."

What's "reasonably long" ?

patto

3-Dec-2012
7:53:04 PM

On 3/12/2012 TonyB wrote:
>What's "reasonably long" ?

Last time I responded to that question I was arrested!

Jim Titt

4-Dec-2012
12:14:31 AM

On 3/12/2012 ironcheff wrote:
>Teeth are tougher than chalk but is anodising slipperier than bare alloy.
>
>I’m wondering if a brand new tube belay device like an ATC, complete with
>its glossy new anodised finish has less friction than the same device after
>it’s had enough use to the point where the anodised finish has worn off
>the surfaces that make contact with the rope.
>
>Give us your gut feel though if you know of measured test results that
>would be better.

We can´t measure any difference in the friction of nylon on anodised aluminium, polished aluminium and polished stainless steel and a review of the literature available agrees with this.
You can certainly measure the difference between a brand new dry treated rope and an old wall rope though!

Jim Titt

4-Dec-2012
12:23:43 AM

On 3/12/2012 TonyB wrote:
>On 3/12/2012 egosan wrote:
>>http://www.bolt-products.com/Glue-inBoltDesign.htm
>
>"With only one exception no device available on the market is proven to
>be capable of stopping a climber in a reasonably long factor 2 fall and
>with most devices the belayer risks severe rope burns and loss of control
>even in considerably lower (less than 1) factor falls."
>
>What's "reasonably long" ?

That´s like "how long is a piece of string". It depends on the device, the faller weight, the rope, the belayers hand strength and the belayers ability to withstand skin burns. There are a couple of ways of defining when the critical point is reached, Petzl use the energy going into the braking hand based on medical work to do with friction burns, the DAV and CAI use a simpler length of slip through the braking hand based on experience in drop testing with humans and experience of accidents.
Avoiding long falls or wearing suitable protective gloves are the recommended way of avoiding finding out what is too long.

There are 13 messages in this topic.