Bobby Hutton and John Fioroni broke some cave anchors. They tested the Climbing Technology's Soft Anchors and also the homemade ones by Andrzej Rudkowski.
CT's dyneema broke at 14kn without affecting the circle anchor. They rethreaded it with 4mm Marlow max sk99 and the dyneema broke at 16kn and in tension broke at 11kn. The circle was mostly unaffected.
Soft Shackle homemade anchor broke the metal round stock at 18kn, then the soft shackle at 23kn and then the bolt itself at 25kn but when pulled in tension, the soft shackle destroys the circle at 17kn.
We also tested some random clown hangers I had laying around. They get installed with the rope around the actual bolt stud but are shaped to prevent sharp edges on the rope. Since there is very little pressure on the hanger itself the broke the ropes first and at super good enough forces. I'm quite impressed how strong they are and would totally rappel on them. However, I don't think they are available anymore.
Behind the Scenes
I had these homemade soft shackle cave anchors laying around for well over a year, maybe even two. I don't just make episodes (anymore) out of obligation. It has to be interesting, have some story, and be worth watching to enough people. What is nice about some obscure things like lightweight cave anchors is we were able to get Climbing Technology's version and clown hangers and even got John, who actually uses them, to talk about them and their uses so this turned out to be a "full value" episode on the topic.