I don’t know who Molly S. is, only that she helped me at Grainger Catalog chat help. I’ve been making wire brushes that have the steel bristles sticking straight out the end, but like other wire brushes, they wear out, and I consider them disposables. I spent an hour or two searching online for ready made ones, but the closest I could find were brushes made for putting texture into wet clay. I was skeptical about their compatibility with what I’m doing, which is to clean difficult to reach areas where paint stripper has been applied.
I did find one company that would make custom wire brushes, but I would have to order hundreds of them. One thing they offered was loose wire bristles, but again, I would have to order a huge quantity, and then make the brushes myself. So I called Grainger Co, knowing they have a huge inventory, and hoping they might have what I needed.
I was looking through page after page of wire brushes, until my eyes were glazing over, then a side box asked if I would like chat help. I decided to ty it. Molly S. was the gal on the other end. She found a brush that mounts in a drill, but it was too big around. she asked if she could help with anything else, and I asked about loose bristles, which they didn’t have, but she asked if I was referring to wire rope (steel cable). immediately I remembered how stiff the wires in cable are, and its narrow diameter. I have hundreds of feet of the stuff outside, not being used. I thanked Molly S. for her help, and tried out the idea. It worked great. It’s fast and cheap. In the pictures you can see how I untwisted part of the rope, and used short pieces of wire to bind the remaining twisted part together. The metal rods are discarded welding rods that have the flux removed. 
