The Effect of Marker on a Middle Mark
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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! |
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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. |
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grog m wrote: I don't want to click on your stuff. Then don't. |
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TLDR it's cool to use a sharpie. |
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Tim, FYI: Video RDA01 may have not uploaded properly as it will not play via Google Drive. The rest play fine. THANK YOU. |
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@Shaniac: Thanks, I deleted and re-uploaded the video. Should work now, thanks for the heads up! |
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9.2.2..... the perennial problem, right? |
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@Christian: Yeah, that's why I'm not going to spend any more time on markers :P |
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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? |
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@Nick: I'm working to get them on YouTube now... |
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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. |
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did any of your tests break at a place other than the knott? |
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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. |
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I'll be busy for the next several hours but plan on replying to your comments tonight! Thanks in advance for reading. |
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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. |
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Well done Sir. |
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All fun & games No new ` news the fact that you all are still breaking relatively new cord is ..... Kind of beating the snot out of a dead horse, don't ya think? https://www.blackdiamondequipment.com/en_US/experience-story?cid=qc-lab-old-vs-new-gear-testing 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 ,,,So ? Please accept my apologies, I have sent you a decoding ring is in the Mail ,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,It seems appropriate; Thanks for your service of choice. . ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, 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 Most likely ..... "I shore missed it" I know, "I sure did" |
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@ 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? |
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You should be testing the Sharpie TEC - Trace Element Certified marker. It is certified to have less than 200ppm of chlorides and halogens. |
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@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". |