QC LAB: THE ELECTRIC HARNESS ACID TEST

Our Quality crew investigates a mysterious harness failure and dives into the effects of chemical contamination on climbing textiles.

Dear BD,

I recently got into indoor climbing about a year ago and have used my BD harness approximately 50-70 times since then. Yesterday I went top-roping at my local gym and as I was being lowered, I heard a pop. I looked down to see that my harness has ripped off in the waist. I felt myself falling backwards so immediately grabbed the rope and was lowered safely to the ground. I have kept the harness in pristine condition in my gym bag and it has never been abused or used outdoors.

This is a paraphrase from a portion of an email I recently received. Sure I get emails that cause concern, but this was a new one entirely—what did “ripped off in the waist” mean? Was the harness not buckled? Did the webbing cut? Was it pilot error? Was there some sort of manufacturing error? I immediately contacted the customer and asked for some photos, as well as traceability information from the tags on the harness. From this info I was able to tell exactly when the harness was made, the traceability to all raw materials and manufacturing processes and cross reference raw material and finished goods batch testing data. All records and testing results showed nothing out of the ordinary. Below is the photo the customer sent us.

INITIAL EXAMINATION

Wow. This ranks up there as one of the weirdest issues we’ve seen. Where the harness broke, it literally looked like the nylon thread had simply melted away. The remaining polyester webbing of the waistbelt was left perforated with remnants of pink coloring. The nylon belay loop had a pink tinge, and the belay loop’s nylon tacks were also pink. In some areas of the harness, the nylon thread tacks were still grey, whereas in other areas, the thread, and only the thread, had turned pink, but was still intact. I grabbed the harness at the visually intact but pink tacks and EASILY pulled them apart by hand. The pink thread had almost no structural integrity. It appeared that the pink was a true indicator of some kind of contamination. As well, the aluminum buckle was showing visible signs of corrosion. It was time to get all CSI (Climbing Scene Investigation).

After a few trips to the grocery store, hardware store & a pet shop, Kevin had a makeshift chem lab set up. Of course we couldn’t test everything, but we tried to choose chemicals with the highest concentration of acid giving us a higher probability of seeing some sort of reaction. The goal was to apply these chemicals to similar harnesses and:

a) see if the nylon thread turned pink (our believed indicator) while not affecting the polyester webbing
b) determine if they weakened the structural integrity to a point where it would fail at extremely low loads.

In the meantime we were in contact with the customer on several occasions, trying to get a more complete picture of the history of the harness—how it was used, where it was stored, any opportunities for chemical contamination. He said it was always in his gym bag either in the trunk of his car or in his house, or of course wearing it at the gym. It had never been left anywhere and he had never worn it outside. Sure there were some instances where there were some groceries and cleaning supplies, etc. in the trunk at the same time, but nothing that noticeably leaked, and likely nothing with an acid concentration high enough to attack the nylon threads.

While Kevin was performing his comparative chemical experiments, we sent the customer’s actual harness off to a lab that specializes in analyzing chemical composition and contamination. We were hoping they could narrow down the contaminant and suggest possible common items with a concentration of acid high enough that it could affect nylon as we saw.

Ah ha. A smoking gun or guns? Out of all the different chemicals that we applied to the harnesses, two turned the nylon tacks instantly pink—muriatic acid, which contains 14.5% hydrochloric acid, and pH Adjuster, which is used to clean aquariums, and contains varying amounts of sulphuric acid, depending on how you mix it. The sample harnesses with these two chemicals looked almost identical to the customer’s contaminated harness.

FURTHER TESTING

Seeing as we had all of these chemicals around, and had learned a bit about certain chemicals affecting nylon and not polyester, we decided to do a controlled experiment to see if, and by how much, these chemicals affect nylon slings and, while we’re at it, Dyneema. The point was hopefully to shed some light on some common questions we get like, ‘I got some acetone on some slings,’ or ‘I accidentaly got some WD-40 on my cam slings while cleaning them – do I need to be worried?’.

Once again—no massive, PhD-level scientific experiment here, just one sample of each:

First round: each sample soaked in the chemical for 30 minutes, dried for 15 minutes, and was then tested to failure. Based on these results, we picked the chemicals that showed some significant signs of degradation to the materials and did another more intense round of experiments.

Second round: each sample soaked in the chemical for 72 hours, dried for 24 hours, and was then tested to failure.

It’s difficult to make any concrete conclusions as we tested only one of each sample, but it’s obvious that the chemicals that affected the strength of the materials the most were:
1) muriatic acid (basically hydrochloric acid)
2) aquarium cleaner (pH adjuster, contains sulphuric acid)
3) bleach

FINAL TESTING

Now that we had validated both muriatic and sulphuric acids as having a catastrophic effects on materials as well as being a match for the change in thread color, we chose to test them on the actual structural integrity of a harness. Kevin contaminated portions of a few full harnesses and tested them to failure to see just how they would perform.

Check out the video below for a visual recap of testing these affected waistbelts in our in-house tensile tester.

CONCLUSIONS

We learned that the gray nylon thread turns pink when contaminated with acid. Why exactly this is at the molecular level we didn’t dig too deeply – but it was cool, and ended up being a great indicator in this case which really helped focus the investigation quickly to acids.

We were able to re-create the visual and structural degradation of the customer’s harness by exposing similar harnesses to sulphuric acid. And therefore though we do believe the customer’s harness to have been contaminated by some sulphuric acid, unfortunately he/we could not determine exactly which chemical or how it became exposed.

BOTTOM LINE

Several years ago there was a rope incident and after analysis it ended up looking like the rope was somehow contaminated with acid. How the rope actually came in contact was never determined. So this is the second incident I’ve personally looked into regarding chemical contamination of climbing gear – and luckily in both cases no one was hurt. Also in both cases, the end result was that the customer doesn’t really know how this chemical contamination occurred. Scary.

Further testing showed that as one would think, acids had a much greater detrimental affect on the nylons and Dyneema than the other chemicals tested.
As well the duration of exposure played a role in strength reduction of nylon and Dyneema, especially when looking at the acids.