The Effect of Marker on a Middle Mark

Hello! I did my own testing about marking the middle of a climbing rope using various markers. I conditioned the samples before pull testing them for added fun!

You can read my full report and watch some videos of the testing from these locations:

Google Drive
https://drive.google.com/open?id=1FPo93rasNu0dK0fLUtos-nc3OdeYSN63

Dropbox:
https://www.dropbox.com/sh/j7bt680j3zm7pye/AACaxJVlCWrx70jBfhOQ94RYa?dl=0

Please let me know if both links don’t work for you.

I thought about summarizing my testing but decided that this issue cannot be digested piecemeal. I welcome constructive criticism and helpful feedback. Thanks!

Please just put a summary sentence or two here with your conclusions. I don't want to click on your stuff. If you can't summarize your findings into a conclusion then you don't understand your data or analysis. 

grog m wrote: I don't want to click on your stuff.

Then don't.

TLDR it's cool to use a sharpie. 

Tim, FYI: Video RDA01 may have not uploaded properly as it will not play via Google Drive. The rest play fine. THANK YOU. 

@Shaniac: Thanks, I deleted and re-uploaded the video. Should work now, thanks for the heads up!

9.2.2..... the perennial problem, right?
Nice work, Tim. Thanks for putting your time into this

@Christian: Yeah, that's why I'm not going to spend any more time on markers :P
Now sewing yarn/floss through the middle is on my mind! I hope to find time to test that.
Thank you kindly!

Your videos won't work. maybe I don't have fast enough connection?    personally I was never able to get the rope to break at the middle mark.  My ropes always broke at a knott or over a sharp edge. never once on the actual middle mark.  Question, has there ever been a documented case of a middle mark breaking in an actual climbing accident?

@Nick: I'm working to get them on YouTube now...

BDA03
https://youtu.be/ErVLneDXMZQ

NDA03
https://youtu.be/YqvkNaYKIPE

RDA01
https://youtu.be/kKI6IwJye_A

WDA02
https://youtu.be/3i3qG6hMswo

What's your background Tim? I find this work to be very well done. Only thing I would add is standard deviation to your data. Although sample size is small, it would show that the data (although not all data sets are within standard deviation) is almost identical or have negligible differences. Although there is most likely no standard for tensile testing of rope with marker, usually standardized tensile testing uses a sample size of 5 (which was most likely not possible because you had only this one rope). I thought this was an interesting read.

Cheers!

did any of your tests break at a place other than the knott?

Interesting work.  I think the UV exposure part of your testing may be questionable since most plastic films block most UVB/UVC.  Since you put the rope samples inside plastic bags for sun exposure, they may not have seen much of the lower WL UVs.   Also, I think it would have been interesting to test samples marked with the more common office-supply variety of permanent markers.

I'll be busy for the next several hours but plan on replying to your comments tonight! Thanks in advance for reading.

I tested several old ropes that had had the middle mark refreshed several times over 3 and 4 years of use. both half and single ropes. the half ropes had middle marks for  when I used them as rappel ropes  for ice soloing as well as used them as single ropes for easy alpine.  None of them broke at the middle marker. they all broke at the figure eight, over hand or bowline that I used in my testes.   I would Never put a sharpie middle mark in an actual knott. When using these ropes as fixed lines for rope soloing when you tie a fig 8 in the middle and drape both ends so you can have a gri gri on one strand and back tie on the other or run a different device on the other rope I simply shift my middle anchor knot a few inches one way or another so that the sharpie mark is not in the knot. 

Well done Sir.
A very thorough examination indeed.
May I suggest that you use Litmus paper to determine the pH of the marker formulation. I think you can also purchase 'blue' and 'red' Litmus paper which provides an immediate indication of acid/alkali.
I've seen and read several of these reports but for one reason or another - pH has not been mapped to the test results.
(It is well known that acids have a destructive effect on synthetic fibre human-rated ropes).
At the opposite end of the scale, alkaline substances may not have a measurable effect.
In any case, determining the pH of the test article will provide additional insight...
As you pointed out, the manufacturer can change their formulation without notice - so a way to determine the pH (cheaply and quickly) would be beneficial. If we had data points mapped to pH - this could be useful...

 All fun & games

No new  ` news

 the fact that you all are still breaking relatively new cord is ..... 

 I have 65-year-old Goldline & 40+ yr old 8.8 Edlwiese 1/2 rope  .  .  . ....

No.. You can't have any of it to break  

Do you have some aged webbing that has been exposed under differing conditions of stress?
Varying the amount of time out in the weather, in weighted/un-weighted circumstances?
 a true test of what one finds in the wild.... the amount of energy need to break those would be interesting.

THERE HAVE BEEN TESTS & ANADOTALLY, THAT SHOW OVER THE LIFE-USE OF THE CORD -
THE MIDDLE MARK SHOWS DUST/DIRT PARTICLES COLLECTING AT A GREATER RATE THEN THE UN-MARKED SECTIONS.

Repeat after me

 Today, the properties of nylons when bundled together to form modern Life-Line rated saftey cord - is safe for all free climbing and most aid climbing
 If you manage to generate the sort of forces that cause a rupture in a saftey=rated cord you will have other fatal issues to deal with.

Ropes rupture at the bends made by knots & they "cut" = are compromised by narrow bends over small radius edges
 & While "loaded" they cut surprisingly easily  .  .  . YMMV.

Break all the stuff you want,
you will eventually have data with enough anomalies to prove whatever you want.
There is already some bozo who says his flawed "science" proves things as new as 3yrs old are too old. . . total BS
 I'm not going to link the scaremonger who is just a marketing-schill

tooTALLtim 

1st - yes not all that coherent  ~ other than that the breaking of random well cared for cord ~ is a topic that has been beaten into submission

For some reason, the Link to  The Black Diamond Equipment tests article   That was meant to go along with  the above citation  

&- that was the focus of the above post -

 which does appear in the edit window version of the post 
but fails to show up in the post itself?  (Edit: I re- Added The URL addy)

(So the whole 4:20 am post is Garblebase   . .  .  .  .  .) 
,,  ,,  ,,  ,,  ,,  ,,  ,,  ,,  ,,  ,,  ,,  ,,  ,,  ,,  ..  ,,  again Argh!
 //  //  //  //  //  //  //  //  //  //  //  
It was these what did it 

@ Nick G: I did not come across any reports of a rope separating at a middle mark. All of my samples separated at the clove hitches. The testing you did sounds interesting and relevant! Could you share it with us in a formal, well-documented manner?

@Sean B: I have a B.S. in Geology but work as an R&D Lab Tech in an Engineering Department. We were slow this winter and you know what happens when you have a nerd with time on their hands and people wrong on the internet...science!

I did consider adding a standard deviation to my data analysis but did not for a couple reasons: my sample size was indeed small, the mechanism of separation was not consistent (but in real-life effectively the same), and I did not want the focus to be on the straight numbers I got from the load cell. Adding too much back-end processing can give the numbers too much gravitas and distract from the other important factors.

Thank you very much for taking the time to read it and sharing your feedback!

@Eric and Lucie: Thank you for your feedback. I did consider leaving the samples out for sun exposure without bags as I did think that they could reduce or filter the light that the samples were subjected to. But in the end, labeling their bags, taking them outside and bringing them back in without mixing them up was just flat out easier this way. Yep, I could have figured something else out (tags, writing on the ends, &c) but convenience won out. I do agree with your point and would also add that 34.5 hours is likely a small fraction of what sun exposure a rope receives in a typical usage lifetime.

I chose the markers I did for a couple reasons:
-Beal Rope Marker is the only marker that I found that a climbing rope manufacturer is willing to put their name on.
-Sharpie Rub-A-Dub is specifically called out by BlueWater as ok for their ropes. I hope that since Sharpie makes it specifically for fabrics that they keep any harsh chemicals out of it; bets are off on regular Sharpies.
-It’s kinda silly that Beal and Sharpie are the opposite color that is easy to find on a dirty rope. I found the Artline marker and wanted to test it since it shows up better since it’s white!
-I didn’t feel like spending more time and money on other markers that are farther afield.

@Mark G: Thank you kindly! I googled “chemicals that affect nylon” and found a Nylon Compatibility List. The list is huge and contains tons of chemicals I don’t know. I looked up a few and found that both acids and bases have negative effects on nylon. More interestingly, there are probably many chemicals on this list that are neutral (or nearly) on the pH scale and DO have a negative effect on nylon. I’m not a chemist but if you want to go through this list and make sure there aren’t any chemicals with a neutral pH that have a negative effect on nylon, please let us know what you find (don't read that as back-handed, I'd honestly be interested). Also, nylon isn’t the only material used in rope manufacture so you’d have to find out what a specific rope is made of to check what may damage it. Deep hole, yeah? So I don’t think a simple pH litmus paper test will let you know if a marker is ok or not.

Thanks to those with coherent replies! Keep them coming if you like.

You should be testing the Sharpie TEC - Trace Element Certified marker.  It is certified to have less than 200ppm of chlorides and halogens.

https://www.sharpie.com/markers/pro/tec/SHTECBlackFine

@Bruce: Yep, that's what PMI recommends (see Section 3.2.2 of my report). But after looking into it on Sharpie's website, I decided that I didn't care so much about a marker that avoids "chlorides and other halogens that can cause stress corrosion on metals such as stainless steel and titanium".

The Sharpie Rub-A-Dub is made specifically for fabrics and I was therefore more interested in the Rub-A-Dub marker.